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On the Parthenon’s Mathematics, Astronomy

and its Embedded Harmony:

its Skeletal Geometry, Modulus, three Key Triangles and Core Angles

Dimitrios S. Dendrinos

Emeritus Professor, School of Architecture and Urban Design, University of

Kansas, Lawrence, Kansas, USA.

In Residence at Ormond Beach, Florida, USA.

Contact: cbf-jf@earthlink.net

June 29, 2017

The Parthenon restored according to reference [2.1]

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Table of Contents

Abstract

Prolegomena

Brief Summary

Introduction: Towards an Efficient Statement of Parthenon’s Geometry

The Parthenon’s Modulus: its Mathematics and Astronomy

The Parthenon’s Skeleton: its Three Key Right Triangles and Core Angles

Stating the Parthenon’s Optimization Problem and its Heuristics

Primitive Pythagorean Triples and the Parthenon’s Triangles

Conclusions and Suggestions for Further Research

Epilogue

References

Acknowledgements

Legal Notice

The Parthenon restored. Source: [2.2]

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The Parthenon at present, Eastern view. Source of photo: [2.16]

Abstract

A novel view of the Parthenon’s structure is taken in this paper. Instead of analyzing the

Parthenon’s final configuration, either in its various reconstructions or in its current condition,

the study draws the Temple’s 3-d skeletal structure. Based on that sketch plan, the Parthenon’s

modulus and its grid pattern are derived. In closely examining this skeletal morphology, a number

of findings emerge. The Parthenon was built on the basis of a critical ratio and a set of inter-

connected angles, generated by following a set of instructions. Utilizing the sketch plan (the

Parthenon’s skeleton), the paper provides a mathematical optimization formulation, involving an

objective function and a set of constraints. On the basis of that problem, one can derive, through

the associated efficiency conditions, the entire Parthenon structure. Along the way, some topics

of mathematical interest are presented and partially elaborated. Suggestions for further research

are also provided.

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Prolegomena

There are many claims that have been made about various topics surrounding the Parthenon, by

many individuals and agencies over the course of time, since its construction in the middle of the

5th Century BC. In contrast to the monument’s widespread popularity, its gleaming aura and

glamor, its Architecture is clouded in mystery and uncertainty. Even who are the builders and

designers, architects and engineers of this extraordinary structure, is a question that still has a

fuzzy response. Time has been rough on the monument, as humans and Nature have taken their

toll on it. Yet, much of the structure still stands, in defiance and in spite of the ravages of time.

A few things, among the many over which we still seem to be plagued by a fair amount of doubt,

are somewhat clear. Architects ΚΑΛΛΙΚΡΑΤΗΣ and ΙΚΤΙΝΟΣ were the, known now, architects of

the Temple. ΙΚΤΙΝΟΣ, who also built the Temple of ΕΠΙΚΟΥΡΙΟΣ ΑΠΟΛΛΩΝ at ΒΑΣΣΑΙ

contemporaneously with the Parthenon, wrote a book about the structure, in which he laid out

the “proportions” he implanted on it. But, unfortunately, the book didn’t survive and only parts

of the final structure did. Hence, the contemporary Architecture students, scholars and

detectives are confronted with a Herculean task. Putting the pieces of the complex Parthenon

puzzle together still remains a formidable task. The careful analyst still has his/her work cut out

for him/her.

Within this mindset then, one must approach the study reported here and its findings. The debate

still rages on, as to what were these “proportions” ΙΚΤΙΝΟΣ sought to implant on the Parthenon

and exactly where and how. Hopefully here, one might find some answers, not contemplated by

previous studies. These answers might be surprising, as they come from an unexpected source.

They are not found at the Parthenon’s final structure, but at its skeleton – the sketches that

probably the architects drew when contemplating and planning the Temple’s construction and

designing its morphology. In that skeletal structure, one discerns significant mathematical

sophistication, in both Geometry and Calculus, incorporated into the structure’s form.

This study finds that the “proportions” ΙΚΤΙΝΟΣ strived to attain and embed on the Parthenon

involve lengths, angles and instructions of how to derive them. The length part of the proportions

is hidden deep in the Parthenon’s structure, close to its sacred spot where the sculpture by

ΦΕΙΔΙΑΣ of goddess ΑΘΗΝΑ ΠΑΡΘΕΝΟΣ was set to stand, inside the ΝΑΟΣ. The angles and the

instructions on how to generate them on the other hand, figure prominently and are based on

the very orientation and the pediments of the Temple on the ΑΚΡΟΠΟΛΙΣ of Athens for all to see.

We do not possess evidence that the architects of the Parthenon were familiar with either

Operations Research methods, algorithmic Computing, or modern-day Genetics and DNA. Yet,

they apparently had a very strong intuitive understanding of the basics involved in these

mathematical methods and biological processes. It is the purpose of this paper to make this case.

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Brief Summary

The thesis is advanced in this paper that one could potentially view the design of the Parthenon

as a solution to an optimization problem. For the first time, to the author’s knowledge, an

attempt is made to derive the Parthenon’s exact site plan (floor plan) and elevations morphology,

including the Temple’s precise orientation, as the optimal solution to a problem drawn from the

Mathematical Theory of Optimization. This Optimization problem’s objective function has a

specific (albeit abstract) interpretation: Harmony. The paper argues the thesis that the architects

of the Parthenon ΚΑΛΛΙΚΡΑΤΗΣ and ΙΚΤΙΝΟΣ derived the 3-d skeletal form of the jewel of Classical

Greek Temples, as the outcome of a general (potentially applicable to all Classical Greek Temples)

optimizing process. Two major sets of findings are reported. A third set involves findings that

potentially open up new landscapes for further future research in Mathematics.

First, and foremost, is the set of findings associated with the efficiency conditions for deriving the

Parthenon’s optimal 3-d skeletal Geometry. Parthenon’s structure efficiency conditions operate

under maximization of an objective function with a concrete interpretation: to maximize

harmonious links among the basic elements of the entire Temple. To state the efficiency

conditions and the essence of the objective function they obey, the paper discusses at some

length the specific variables defining the modular three-dimensional structure of the Parthenon’s

skeletal form and its average cubic grid pattern. It presents the precise manner in which the

absolutely necessary and sufficient mathematical (geometric and algebraic) design specifications

are set, expressed as variables and conditions they obey. These conditions are responsible for

the Parthenon’s 3-d grid. Further, the general form of the problem’s objective function is stated.

It is concluded that a far more advanced and complex set of instructions can be discerned in the

design of the Parthenon’s 3-d skeletal structure, than merely the seemingly a priori and largely

ad hoc determination of its major elements including the total number of columns at the peristyle

(46), their 8x17 split in the Parthenon’s narrow and long sides, various inter-columnia, the

Temple’s 3-d measurements, and the Temple’s orientation. It is proposed (and proved in the

paper) that the fundamental Geometry of the Parthenon and the edifice’s 3-d modular grid were

based on three key right triangles, their three core angles, and their spatial interconnections. Of

special note is a core angle of 22.5 in a right triangle associated with the Parthenon’s orientation,

representing exactly one sixteenth of 360; and an exact ratio of 1.50 associated with the

Parthenon’s barycenter and omphalos – the location of ΦΕΙΔΙΑΣ sculpture of ΑΘΗΝΑ ΠΑΡΘΕΝΟΣ.

The second set of findings identify the Astronomy related objective held by the Parthenon’s

architects. It is demonstrated that the orientation of a key Parthenon axis’ front end is towards

the sunrise rays of the Summer Solstice; and the concomitant orientation on the other end of

this key axis is towards the last glim rays during the Winter Solstice. A third set of findings is linked

to the Parthenon’s floor plan design and its 2-d modular grid skeletal structure. It involves some

Number Theory aspects of the Temple’s 46 (in a split of 8x17) columns, comprising its peristyle.

Finally, whether the key right triangles of the Parthenon belong to the class of right triangles

called “Primitive Pythagorean triples” is explored, and some preliminary findings reported.

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Introduction: Towards an Efficient Statement of Parthenon’s Geometry

The Parthenon’s skeletal Geometry and its modulus

Why does the Parthenon have 46 columns at its peristyle of about 1.90 meters in diameter (the

four corner columns being slightly, by 1/40th, larger than the other 42)? Why are there eight

columns in the frontal (Eastern) and back (Western) sides of the Temple, and seventeen columns

on each of its North and South sides? Why do the columns stand at about 10.40 meters high?

Why is the Parthenon’s Eastern/Western side (at the ground level of the crepidoma) about 31

meters (actually the Eastern side is a bit shorter than the Western side – 30.875/30.884), while

the Northern/Southern is about 70 meters long (again, there is some minor differences, as the

Northern side is slightly longer – 69.5151 – than the Southern side - 69.5115)? Why does the

Parthenon’s main (long, East – West) axis is at about an 80 azimuth and not at a due East – West

axis (like almost all Doric Classical Greek Temples – the Temple of ΕΠΙΚΟΥΡΙΟΣ ΑΠΟΛΛΩΝ at

ΒΑΣΣΑΙ notwithstanding)? These are the kind of questions we are set to explore in this paper.

A framework one may be able to adopt or wish to employ in seeking answers to such basic

questions is none other than the field referred to as “Operations Research” or more formally, the

“Mathematical Theory of Optimization”. Of course, Engineering related concerns (primarily

having to do with designing a structure that could support the Temple’s roof) must have been

involved in such decisions by the two architects of the Parthenon, ΚΑΛΛΙΚΡΑΤΗΣ and ΙΚΤΙΝΟΣ,

and the Temple’s engineers in building a structure with the specifications we currently observe

imprinted on it. Moreover, setting aside for the moment the Engineering and Topography related

issues facing the Parthenon’s builders, Architecture and Art related factors, we do know, did play

a major role and did enter a calculus in the design of a structure in which attention to detail was

of paramount importance, and where Harmony was sought in its proportions at all levels of scale,

from the miniscule to the grand. The enormous literature on the Parthenon is replete with

references to these types of analyses. This paper will attempt to neither review nor supplant this

plethora of studies and their wide scope.

However, no matter the voluminous work on the multiple subjects concerning the Parthenon,

perhaps the best studied monument of the ancient World, no study does, or even attempts to,

answer the basic questions posed at the beginning of this Introduction. In addition, a careful and

systematic consideration of the numerous ancient (used in Athens during its Golden Age) units

of measurement (in length, area and volume) fail to exactly reproduce key elements of the

Parthenon. Measurements of (for example) the Parthenon’s 3-d sizes do not come up to be exact

fractions or multiples of the abundance of units employed back then, as it will be demonstrated.

Why is it so, when such meticulous attention to detail was a hallmark of the Temple’s

Architecture? Is it possible, that we are not measuring the real quantities that determined them?

Hence, one is left pondering these questions. So, here an attempt is made to systematically

address the issue of Parthenon’s construction from a different angle, as the solution to a problem

from an Optimum Design perspective. Hence, the hypothesis is suggested that there must have

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been, in short, certain variables – such as inter-columnia and columns’ diameters - that on their

average (and possibly on an individual level) somehow optimized a function subject to

constraints, the nature of which (objective function and constraints) can be and are subject of

this work, drawn from shown and manifest evidence.

By looking at the Parthenon (as is the case with any architectonic structure) one must ask a

number of existential questions (and then attempt to find some answers). This genre of

questions, introductory to an extent, may be the following. Why was the Temple built there, at

that specific site and location with that specific orientation and not at a marginally neighboring

one with a slightly different orientation? Why do the Temple’s elements have these exact

(whatever that “exact” may entail) sizes and not marginally different (smaller or greater) ones?

The same set of questions but with the “marginally neighboring” expression substituted by

“significantly different”, so that the question becomes ‘why was it not built at a significantly

different location, with a significantly different orientation’, or ‘why built it at all’, or “why not

having elements with significantly different sizes” etc., clearly fall outside the purview of this

study. But to the extent that they are posed ‘at the margins’, they remain valid (and potentially

insightful) questions to ask and ponder.

A similar (and again never posed by anyone to this date) question is this: What is the skeletal

structure of the Parthenon? Is it possible that the architects of the Parthenon were precise and

exact at that architectonic preliminary drawings (sketch) phase? Was it there the opportunity to

obey the then current units of measurement in lengths, area and volume, and then (once the

building acquired its final form and the masonry construction was dressed and all construction

adjustments finished), the ensued measurements disappeared under the dressing, carving,

imperfections and all other factors forcing differentiation and breakup of the homogeneity and

conformity to a standard, and consequently what was left were approximations at the margins?

Could that be a statement with social underpinnings? Is in the diversity of the Parthenon’s

columns and their inter-columnia a declaration of all individuals being marginally different

although in unison and collectively performing one function, supporting the Parthenon’s roof?

Larger in scope questions may also be posed. Why does the Parthenon have these exact length,

width, and height specifications? The Temple could possibly be constructed maintaining the exact

same ratios it does possess at this scale, but at a marginally different size (either slightly smaller

or bigger). Why at the size it currently stands? Is the answer to this question of a socio-economic-

cultural type, say for instance an optimum in total expenses due to finance related constraints or

maybe resource related constraints? Or is the answer purely architectonic and based on

Aesthetics? One will obviously say, it was both. But exactly how? Continuing along these lines,

why does the Parthenon have a system of 8x17 columns at its peristyle, with a ratio

R=17/8=2.125 (where the four corner columns are counted twice), a ratio critical in the

discussion of Greek Classical (early, middle or late) Temples, and not any other? Some say, that

this is simply the outcome of 8x2+1=17. But this doesn’t really answer the questions: why 8? And

why 8x2+1? These, largely vacuous, answers describe the obvious, without explaining it.

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Numerous similar questions one may ask, along the lines suggested. But those posed certainly

must figure prominently in one’s architectural and Engineering approach to the Parthenon (or

any other Temple of Classical Greece). It turns out that a number (if not all) of the above

questions can be answered adequately, if one examines the appropriate modulus and a 7x16

average grid pattern under which the Parthenon’s skeleton was put together, and what lies

underneath that modulus in the Parthenon’s skeletal structure. By so doing, one can approach

the Temple’s construction on the basis of a set of optimality subject to constraints conditions

involving the skeleton and its modulus. In turn, the associated efficiency conditions can show

how that modulus was derived. It turns out that it was made on the basis of three key constituent

right triangles and their three core angles, and a ratio involving two key lengths.

Number Theory and the Efficiency conditions of an Optimization Problem for CGTs

Subjects related to the Parthenon’s modulus, along with other quantitative features of this

Temple and other Classical Greek Temples (CGTs) have been addressed by this author in a

number of contexts, see for example [1.1]. There, the role shadows played in the design of the

Parthenon and a number of other CGTs was explored and identified. Also analyzed there was a

number of key ratios embedded into the design of the Parthenon and four other CGTs, as well as

discussion and documentation was supplied on the modular structure of these Temples. As a

result of this analysis, the basis was set for a statistical approach to their design specifications,

and towards the derivation of a typology in the CGTs architectonic morphology.

This paper is a continuation of reference [1.1], where references to prior and existing literature

on the Parthenon are found. Material from that paper will not be duplicated here, but simply

extended and to an extent revised. Such modifications will be accomplished by a more in depth

look into the pinnacle of Classical Greek Architecture, and by analyzing from a novel perspective

this great monumental structure, designed by architects Callikratis (ΚΑΛΛΙΚΡΑΤΗΣ) and Ictinos

(ΙΚΤΙΝΟΣ), the Parthenon. Much has been written about the Architecture of the Parthenon since

Vitruvius, and especially during the past two centuries. Not much of that literature will be

repeated here. Some of that has been reviewed in [1.1]. The interested reader may consult for

informative introduction references [2.9], [2.10], [2.15] and references therein.

That literature however, to the extent that it delves on the basics of the Parthenon (like for

instance its modular structure), doesn’t approach the subject on a proper basis. In most cases

the erroneous Vitruvius assertion about the modular structure of CGTs is adopted. The vast

majority of the existing treatises tend to look at the Parthenon by examining the actual

dimensions (length, width, height) of the structure. In them, ratios of different types (the Golden

Ratio for instance) have been sought as intentionally having been implanted in the structure. This

work does not intend to refute the validity of some of these assertions.

This author is neutral on their validity, as questions about measurements and approximations

can’t be ascertained in toto. Instead of placing emphasis on the simple and obvious quantities,

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like for instance the Parthenon’s external 3-d sizes, a look into the deeper skeletal design of the

monument will be taken. It is suggested (and documented) that such underlying skeletal

structure was drafted with a great deal of care and attention to detail, and at its core it obeys

exact quantities (angles and ratios) not approximations on lengths. Underlying skeletal

morphology coupled with a set of instructions give rise to these surface ratios and to the overall

Parthenon form. It is demonstrated here, that by looking into the skeleton of the Parthenon, its

modulus and average grid pattern involving its constituent elements (three key triangles and

their core angles plus a key ratio involving length), a set of complex instructions are uncovered

and a huge amount of information is stored. This depository of instructions is uncovered here, as

it has been overlooked by conventional approaches to the Architecture of the Parthenon.

Central in this quest is the uncovering of the efficiency conditions found to govern the basic

Geometry of the Parthenon’s skeletal structure. This angle, on how one can derive the Temple’s

design specifications by analyzing its skeleton (a structure’s DNA to use a convenient analogy),

leads towards stating the Mathematical Optimization Theory based problem of Classical Greek

Temples’ morphology. In effect, the CGTs can be approached as the optimum solution to a

comprehensive (entailing most quantities of a CGT’s architectonic form) optimization problem.

It has been suggested by the author (and in contrast to the generally adopted Vitruvius view of a

Greek Temple’s modular structure – namely that the modulus of a Greek Temple is the distance

between two columns at their base on the stylobate) that the proper definition of a CGT’s 2-d

modulus is the average distance between two columns’ very center. The 3-d manifestation of

the modulus is then derived from the height of a column (including the capital), i.e., the distance

between the crepidoma’s stylobate from the entablature’s lowest level (the bottom of the

Temple’s frieze). It is reminded that the Parthenon’s columns do not have a base. They also sport

different (some minute, some considerable) distances between any pair of them on any side.

By closely analyzing the modular structure of the Parthenon under this angle, some Number

Theory related issues immediately emerge. Further, a better understanding is obtained as to why

the architects of the Parthenon chose this particular 8x17 split of the peristyle’s four colonnade

segments (East, West, North, South) of 46 columns in toto. In approaching the subject of a 3-d

modular structure of the Parthenon in accordance with the suggestions first put forward by this

author in reference [1.1], one can derive an efficient mathematical method to define and arrive

at the Parthenon’s skeletal geometric structure including the columns’ spatial arrangement (46,

8x17). It will be shown how the unfolding of the structure is pegged to efficiency conditions.

Obviously, to derive such geometric efficiency conditions, aspects of sufficient approximation to

actual measurements of the Parthenon’s structure are of critical importance. See for instance

reference [2.10], [2.15] in which the almost miniscule differences in the Parthenon’s crepidoma

East/West and North/South lengths are listed. In [1.1] the author argued that it is not possible

for a Classical Greek Temple (any Temple, not just the Parthenon) to have identical (at a set level

of approximation of, say, the millimeter) E/W or N/S length sizes, or column widths and heights,

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or any quantity which is to be reproduced. The demon of construction imperfections doesn’t

allow it. These differences were unavoidable back then, as they are to a lesser extent today.

However, this is not the sole reason why differences, as those recorded in the Parthenon’s inter-

columnia, are observed see [2.15]. Engineering related considerations dictated very likely the

inter-columnium differences with columns next to the corner columns significantly differing with

respect to inter-columnia. On top of that, and remaining on this example, with regards to same

side inter-columnia differences, one can’t fail but to notice the discrepancies characterizing

measurements of the same distances derived by different researchers. As the author has argued

in the past, Quantum Mechanics theoretic reasons might underlie such differentials, see [1.5].

This is a fortiori a reason why, statistical averages must be considered. It is on statistical averages

that the narrative here proceeds. Using such averages, an aggregate approach can be undertaken

(whereby some averages are computed and their average effect ascertained). In the optimum

design framework adopted here, however, some disaggregation can be accommodated (where

some classes of variables, like for instance various types of inter-columnia) can be considered

and their sizes and effects endogenously computed.

In any case, the author has limited access to detailed and precise measurements, and no means

to independently derive them. Hence, this paper can be construed as a first attempt towards

achieving this goal, of stating the architectural structure design specifications as an optimal

design problem and supply, to the extent possible and based on available evidence, convincing

(although not beyond reasonable doubt) evidence to justify the claim and the findings.

Subsequent attempts by other researchers, with access to more accurate measurements and

computing capabilities, are of course needed and scientifically necessary in replicating the

findings reported here and thus provide support to the claims made.

Having supplied this caveat, it must also be noted that due to the nature of the enterprise (the

search for exact ratios and exact counts on angles) and the finding of these building blocks, the

work reported here seems very promising. The paper presents the formal mathematical

statement of the (aggregate and disaggregated) optimum design and orientation of the

Parthenon in the final section of the paper. Due to the Mathematics required to follow the

exposition, it can be construed as an Appendix and available to those readers familiar with the

basic elements of Optimization Theory and with the Operations Research literature.

Related to the inherent difficulties involving accuracy in measurements, is the subject of entasis.

In Doric Temples’ entasis (ΕΝΤΑΣΙΣ, tension) related effects were structurally reflected by: a slight

inward leaning of the columns; by the frontal and sideways slight inward concavity and upwardly

directed convexity of the crepidoma); by the slightly uneven diameter at the four corner columns

from the rest of the peristyle’s columns; by a smaller inter-columnium between the corner

columns and their neighboring ones than the average; and by the slightly uneven diameter on all

columns along their vertical unfolding.

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All these variations are not incorporated into the analysis that follows. Such architectonic and

engineering detail can only be incorporated into the present mathematical (geometric and

algebraic) analysis when the precision by which the various relevant Temple dimensions (such as

the total frontal and side lengths, as well as the columns’ height) enjoy equal confidence in

measurement approximations. At the level of approximation in measurements contained in this

paper, these fine details built into the Parthenon’s structure (for both, Art/Aesthetic as well as

Engineering/Architecture, structural/material support involving weights and loads, lateral and

vertical forces related factors) can be with ease bypassed at this stage. These aspects of a CGT’s

Architecture and Engineering are in part presented and discussed in [1.1] and widely elaborated

in the existing literature on the Parthenon. Again, here the emphasis and the focus is on the

skeletal (sketch drawn) structure of the Temple.

Towards a Further Understanding of the Parthenon’s Astronomy

Building on the Astronomy related considerations identified in reference [1.1] by the author, a

closer look is taken into the orientation of the key triangles identified as being at the basis of the

Temple’s structure and appearing in its skeletal configuration. It is concluded that these triangles,

and especially the one responsible for a key diagonal in the rectangular part of the Temple’s

superstructure formed by the peristyle’s 46 columns, are very informative in providing some

evidence as to why the architects of the Parthenon’s decided to orient the edifice the way they

did – which is not exactly in accordance with any major Solar alignment of any other Doric CGT.

Further room for refinement is left in this angle of the exposition, by future work involving more

accurate approximations to the Temple’s three key triangles’ precise orientation.

Primitive Pythagorean Triples and the Parthenon

In the last section of the paper, a search is undertaken to examine whether some key right

triangles this study identifies as constituent elements in the Parthenon’s Architecture are in fact

so-called Primitive Pythagorean Triples (PPTs). This is a set of triangles that exhibit certain

properties of pure mathematical (and thus possibly Aesthetic) interest. The core mathematical

property of the set of PPTs (they comprise a Tree) is that the sides of these right triangles

(expressed in some modular unit) are coprime. The right triangle with sides (3,4,5) is the root of

that Tree, and the best-known PPT. Here, a more specific set of PPTs is examined as to possible

connections to the study’s key right triangles – those with a long side close in length to their

hypotenuse. The outcome of this search at this stage is inconclusive, albeit promising.

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The Parthenon’s Modulus: its Mathematics and Astronomy

In accordance with arguments put forward in [1.1], the 2-d (floor plan) modulus of the Parthenon

(and all CGTs) is found by drawing lines through the very center of the peristyle’s columns, along

an approximately North-South, as well as an approximately East-West direction given that both

the narrow (usually East and West) sides of the Temple, as well as the long (usually North and

South) sides are so oriented. In the specific case of the Parthenon, its 2-d floor plan modulus

forms a grid (the precise dimensions of which will be estimated in a bit) with its border lines going

through the very center of the seventeen Northern and Southern most sides’ columns, and the

eight Eastern and Western most sides’ columns.

Notation and some nomenclature.

For the purpose of this paper, the Parthenon’s peristyle 46 columns (split according to a ratio

R=17/8=2.125, with 17 columns along the North and South sides, and 8 columns along the East

and West sides, corner columns counted twice) will be numbered as follows: the corner column

at the South-Western corner will be designated as column #1; the next columns as #2 and so on,

till the last (North-Western) column which will be designed as column #8. Moving Easterly, the

second column at the Northern side of the Parthenon (and to the East of column #8) will be

column # 9, and so forth till the last column of the Northern side (at the North-Eastern corner of

the Temple) which will be designated as column #24. Consequently, the South-Eastern corner

column will carry the number #31; and the last column of the Parthenon’s peristyle (at the

Eastern side of column #1, and the penultimate Southern column) will carry the number #46.

The very center of the Southwestern corner column #1 will be designated as point A, see diagram

in Figure 1. Moving North, the Western border line of the grid pattern intersects the Parthenon’s

East-West axis of symmetry (designated by the blue line in Figure 1), at point E. The very center

of the South-Eastern corner column #31 will be designated as point B (see Figure 2). At the

Eastern frontal (narrow) side of the Temple, the center of the NE corner column (column #24)

will be designated as point C (see both Figures 1, and 2). The intersection of the modular grid’s

Eastern border line intersects the (approximately) East-West axis of symmetry at point F (see

both Figures 1 and 2). It is noted that this axis of symmetry does not have a due East-West

orientation, as the diagram of Figure 3 demonstrates. The main orientation of the Parthenon is

towards the East North-East at an azimuth of about 80. Inside the cella is the Parthenon’s Naos

(ΝΑΟΣ), which contains the Eastern and main Entrance to the Temple, and the Sekos (ΣΗΚΟΣ),

that has a Western entrance, see Figure 3. Slightly to the West of where the location of the statue

of Athena, sculpted by Phidias, used to stand inside the Naos, the barycenter of the Parthenon’s

floor plan is found, to be designated as point H (see Figures 1, and 2). It is in effect the Temple’s

omphalos, as we shall see that a number of critical for the Temple’s structure intersections occur,

and a key ratio, responsible to a large extent for the Parthenon’s overall morphology, is located

on a line passing through this point H.

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Figure 1. The Parthenon’s floor plan, its 2-d modular and average grid structure. The basic floor

plan diagram is from source [2.3]. Drawing of the modulus and its grid is by the author. North is

almost straight towards the right side of the Figure. The scale of the floor plan is given at the top

of the diagram. At bottom, is the Eastern – and main – Entrance of the Temple. The 2-d sizes of

the modulus, that is the grid pattern (which is not exactly a square), are such that the distances

among East-West running lines are slightly smaller than the distances among North-South

running lines of the grid. The red diagonal line AC shown above has an orientation such that on

the one end it points towards the sunrise during Summer Solstice at Athens; and on the other

end, it aligns with the sunset during Winter Solstice. Blue line EF is the Parthenon’s 2-d axis of

symmetry (approximately in an East-West direction at an azimuth of about 80). Point H is the

Parthenon’s barycenter and omphalos, the point where the two axes intersect. The rectangle

close to point H and to the East is where the statue of Athena by Phidias was located. Source of

Figure 1: the author.

The Temple’s modular structure and Number Theory

Parthenon’s modulus, its grid, and the Temple’s cella. Noticeable are the following (at least)

seven specific connections between the suggested modulus proposed by the author and the key

elements of the Parthenon’s floor plan: (1) the step of the cella’s platform coincides exactly with

the grid line linking the centers of two sets of columns, set #46 and #9, and set of columns #23

and #32; (2) the cella’s Southern wall’s outer surface coincides exactly with the grid line joining

the centers of columns #2 and #30, whereas that of the Northern wall coincides with the grid line

joining the centers of columns #7 and #25; (3) the edges of the two cella’s exterior East-West

(long) walls – the antae - start exactly at the grid lines joining the centers of columns #45 and

#10, and columns #22 and #33; (4) the pair of ten-column sets running on an East-West direction

inside the main space of the cella, the Naos, as well as the six internal columns running on a

North-South direction, all these three sets of columns, align with three grid lines of the modulus,

lines joining the centers of columns #6 with #26, #3 with #29, and #15 with #40; (5) the pair of 6-

column sets at the East and West sides of the Temple on the cella’s stepped up platform and in

front of the antae at the Eastern and Western entrances into the Naos and sekos correspondingly

(at the two porches that is), line up with the grid lines joining the centers of the pair of columns

#9 and #46, and the pair #23 and #32; (6) the front of the base on which the statue of Athena

was set at the interior of Parthenon’s Naos lines up exactly with the grid line joining the centers

of columns #17 and #38; (7) the diaphragmatic wall separating the cella’ Naos from the sekos

aligns precisely with the grid North-South running line joining the centers of columns #14 and

#41. As it can be seen in Figure 1, the two diagonals drawn on the Parthenon’s floor plan go

precisely through the four exterior corners of the cella’s antae. The above evidence leaves little

doubt that this is in fact the Parthenon’s modular structure and grid. In the diagram of Figure 1

the units of the modular grid pattern are equal along the E-W axis, and also equal in the N-S axis.

However, this does not imply that they are necessarily forming a square grid pattern (they don’t).

15

The Parthenon’s modular grid and Number Theory. It must not go unnoticed the fact that,

numbering of columns has some Number Theory related properties. For example, due to the

choice that involved the total number of peristyle columns (46), and their 8x17 rectangular

arrangement, the grid alignments involve two pairs of columns with reversed numbering: #14

and #41, #23 and #32. And, of course, their sum is 55 in both cases.

Another key matchup is that between columns #22 and #33, with a sum of 55, as well. Out of

these examples, some general Number Theory related conclusions can be drawn. Column

numbering of the 8x17 peristyle is such that when the first column is either at the Southwestern

or the Northeastern corner, the sum of all pairs at the East and West sides of the grid is 32; for

example: 1 + 31 = 32; 8 + 24 = 32, and it is remarked that in the number 32, 3+2=5. Whereas the

sum at the North and South sides for all pairs, with the exception of the two (South-Western and

North-Western) columns at the West end of the Temple, is 55 (so that 5+5=10). The totals 32 and

55 will be designated as N1=32, and N2=55.

If the starting column is either at the Northwestern or the Southeastern corner, their sums are

either 64 (on the East-West) or 41 (on the North-South) direction. Both of these sums are such

that (as in the previous case), 6+4=10, and 4+1=5.

Noted is the fact that the properties just outlined (the 5 and 10 sums) are invariant with respect

to the assigned location of the #1 column, as long as #1 column designation is a corner column.

Commutation of the numbering system among columns on this rectangular grid pattern, with a

starting column numbering system at any off-corner point, is of interest. Such commuting

schemes do not produce quantitatively and qualitatively similar sums to those postulated for the

corner-column starting positions.

This variance is meaningful, and with interesting mathematical Number Theory related

extension, when Temples with different peristyles colonnades are so analyzed. For example, in

the case of Temples with a 6x15 (38 total columns, as is the case of Selinunte’s Temple E, analyzed

in [1,1]), or a 6x14 (36 total columns, as is the Temple of Hera II at Paestum, also analyzed in

[1.1]) system of peristyle colonnades. The smaller the total number of columns, the smaller the

East-West, and North-South totals. And the manner these totals are connected, could supply the

basis for a Number Theory approach to the issue.

The import of this Number Theory aspect of the columns’ rectangular configuration will be seen

in the penultimate section of the paper where the Optimization Problem for CGTs will be

addressed. The manner in which these totals, and the columns’ split between the narrow and

long sides of a Temple, could potentially affect the structure and value of the optimization

problem’s objective function. How this is possible it will be pointed out then.

It is hence suggested that the choice of 46 columns at the Parthenon’s peristyle was not totally

independent of these occurrences in and properties of Number Theory. This is a broader topic,

involving formal mathematical analysis in Number Theory, which will not be further elaborated.

It is left to future work and to the interested reader.

16

The Astronomy embedded into the Parthenon’s Design.

The Astronomy built into the Parthenon’s design is depicted by the red line drawn in Figures 1, 2

and 3. Line AC, which joins the centers of columns #1 and #24, is a key feature in the design of

the Parthenon. It is quite close to a 62 azimuth – very close to the azimuth of the Summer

Solstice sunrise at the Athens’ location. The Parthenon is located at Earth’s latitude of about 38

(to be exact at 37.9714N). At that latitude, the sunrise at Summer Solstice occurs at about a 60

azimuth angle or 30 North of the due East-West orientation. The AC axis has an angle (as it will

be shown below, this being one of the three core angles of the Parthenon’s skeletal structure) of

about 22.3 to the Parthenon’s axis of symmetry EF, Figure 1. Given that the inclination of the EF

axis is about 10, see Figure 3, it follows that the AC diagonal axis points to the Summer sunrise

rays at Solstice.

The one or two degrees of possible difference is negligible. Given the uncertainty surrounding

the change in the declination of the ecliptic (as the Earth’s axis of rotation traces an

approximately 26K-year cycle) over the intervening 25 centuries; and in view of any other

competing and compelling rationale for such a deviation from a pure and due East-West

orientation of the Parthenon’s main symmetry axis; it can be asserted with some degree of

confidence that the objective of the Parthenon’s architects Callicratis and Ictinos in sketching out

the blueprint of the Parthenon was to align this key diagonal of the Temple dedicated to goddess

Athena to the sunrise during Summer Solstice on the one end, and to the sunset during Winter

Solstice on the other end. It could be an orientation that the prior to Parthenon Temple had.

Of course, the orientation of the key diagonal line AC leaves one wondering what was the

function (or intent) of the other diagonal’s orientation. Parthenon’s EF main axis of symmetry (at

about 10 North of the due East-West orientation) is understood now (as it will be demonstrated

in more detail in a bit) to have been decided in the pursue (and the result) of a desired AC

orientation. This reason still leaves as an open question the other diagonal’s orientation. Further

aspects regarding the Astronomy built into the Parthenon are discussed and analyzed in [1.1],

whereas the basic issues regarding the Astronomy related shadows of monuments are found in

work by this author in [1.3] and [1.4].

The Parthenon’s 2-d floor plan modulus sizes and some Ancient Greek units of measurement.

From the manner in which the modulus (and associated grid structure) of the Parthenon’s

skeletal structure is now set, one can derive a basic ratio: the number of narrow sides’ modular

units (7) over the number of long sides’ modular units (16), or R’=16/7. This ratio (an important

ratio in the exposition that follows) will be further refined in a bit, by weighing these units

employing their actual average lengths. This ratio must be viewed in conjunction with the

partitioning of columns ratio R=17/8=2.125 (counting corner columns twice) as discussed in an

17

earlier section. Of course, R’ is a function of R. These two ratios, R and R’ are critical in the analysis

that follows.

Ratios, R and R’ are potentially of some mathematical interest as well. They belong to a sequence

containing factors constructed by the following rule: the starting value is the ratio R; the next

term in the sequence be a ratio of a numerator less than a unit from the numerator of the prior

term; the denominator also be less by a unit from that of the prior term’s denominator. It must

be noted that all CGTs’ partitioning of their peristyle’s colonnade and modular units occupy two

consecutive terms in a series within the class of sequences they belong. Each Temple has a

fingerprint type sequence, belonging to a class of Mathematical Sequences where all CGTs with

identical peristyles belong. Each class depends on the peristyle’s narrow/long side number of

columns. The arithmetic values of these sequences are (in discrete steps) exponentially

increasing functions of the order in the sequence.

There are upper and lower bound limits in these sequences. These limits are functions of the

narrow side’s number of columns. Other properties apply as well. For example, bulkier Temples

(more square looking – column-wise than rectangular ones, where T1 is closer to T2) experience

lower upper bounds. In the case of the Parthenon, T2-T1=9; in the case of the Temple of Epicurius

Apollo, built by Ictinos as well, the T2-T1=15-6=9 also; similar to Epicurius Apollo is the difference

and colonnade at Selinunte Temple E (see [1.1]); at Paestum, the Hera I Temple has a difference

of T2-T1=18-9=9, and at Hera II has T2-T1=14-6=8. Further analysis on this topic is left to the

interested reader. Upper bounds of such class of sequences enter the objective function

underlying the efficiency conditions, to be addressed at the last section of the paper.

Inter-columnia.

A major finding of this paper, confirming prior work by the author on this subject, is the existence

of different on the average inter-column distances (the distance is referred to as “inter-

columnium” in the literature) between columns at the narrow (East/West) sides of the

Parthenon, and the long (North/South) sides. Moreover, these inter-columnia are such that the

narrow sides’ average inter-columnium is shorter than that along the longer sides. This sub-

section’s objective is to document this claim. Estimation of this difference will lead to a precise

estimation of the Parthenon’s real modulus and the sizes of its rectangular grid pattern.

To estimate the sizes of the two-dimensional modulus and associated grid of the Parthenon’s

floor plan, one must create a system of equations on two unknowns. It will be shown that the

average distance between columns at the peristyle (ΠΕΡΙΣΤΥΛΙΟΝ) of the Parthenon (and in

almost all CGTs) along the long (usually their Northern and Southern) sides and along the narrow

(usually the Eastern and Western) sides are not identical and neither are the two sizes (East/West

and North/South) of the modulus’ grid.

To do so, and following the algebraic system of equations first presented in [1.1], one need

compute the values of the two variables at both sides of the Temple, having made an estimate

of the sizes of the Temple at the stylobate (ΣΤΥΛΟΒΑΤΗΣ) level:

18

8x + 7y’ = L1 and 17x + 16y” = L2 (1)

where variable x designates the columns’ average diameter at its base on the stylobate (a known

quantity or parameter here); y’ is the value of the average inter-columnium along the narrow

(Eastern and Western) sides; y” is the value of the average inter-columnium along the long

(Northern and Southern) sides; L1 is the length of the Temple at the stylobate along the narrow

sides; and L2 is the length of the Temple at the stylobate along the long sides. This is the simple

linear version of a far more complicated non-linear system on three variable (x, y’, y”) assuming

uniform in diameter columns at all spots of the peristyle and average inter-columnia. The non-

linear comprehensive version of this system of equations in (1) will be presented in the next

section of the paper.

The pair of numbers (7, 16) are the number of spaces among columns at the narrow and long

sides of the Temple correspondingly. If by T1 and T2 we designate the number of columns along

the narrow and long sides of the Parthenon respectively, then:

R=T2/T1=2.125, and R’=(T2-1)/(T1-1). (1.1)

For the Parthenon, and using the current metric system, one obtains the following

measurements, x=1.9 meters; L1=28.50 meters; and L2=66.80 meters. The last two counts have

been estimated by the author and they are based on the diagrams of Figures 1 and 3. The first

count, on the average diameter of the columns’ base (which is measured at the edge of the flutes

of the columns’ shafts), is a widely used count, encountered for instance in reference [2.5] and

its sources. However, the architects of Classical Greece did not use a metric system. Instead they

used an assortment of units to measure lengths, areas, and volumes, see [2.6] for an introduction

to them.

Here a few will be mentioned, of assistance in deriving the measurements of key components of

the Parthenon’s structure, as perceived by the architects and engineers then. They will also be

used as evidence to support a major thesis of this paper: namely that no elements of the

Parthenon’s structure are either exact fractions or multiples of any of these units. This realization

forces the analyst to seek more basic components and processes as being the constituent

elements in the design of the Parthenon, and some of these are identified here. Or, alternatively

to assume that the construction of the Parthenon was not carried out according to a pre-

established plan or blueprint, but it was instead the product of an ongoing improvisation and ad

hoc decision making. Such a hypothesis has been fueled by the considerable (to some) variations

in columns’ diameter and inter-columnia. However, this author rejects the latter hypothesis.

A number of units of measurement used in Ancient Greece, seemingly of import here, are the

following: the pous (ΠΟΥΣ) or “foot”, a unit of about 30.8 centimeters; the lichas (ΛΙΧΑΣ) or “ten

fingers”, a unit of about 19.26 centimeters; the cubit or “pechys” (ΠΗΧΥΣ) or “24 fingers”, a unit

of length measuring about 46.2 centimeters; the single bema (ΒΗΜΑ) or “step”, a unit measuring

about 77 centimeters; the “pace” or a double step, about 154 centimeters; the “fathom”

19

(ΟΡΓΥΙΑ) about 1.85 meters; and the plethron (ΠΛΕΘΡΟΝ) a unit of longer distances, measuring

about 30.80 meters in length.

These units of measuring length are of some use within our scope to interpret and put into

perspective the measurements we obtain in meters or centimeters, along with making the case

for the major thesis to be advanced, just stated. Specifically, we shall see that none of the

Parthenon’s basic structural components (the columns’ diameter or height, the stylobate’ width

and length, etc.) are exact fractions or multiples of (but only close approximations to) any and all

of these units of measuring lengths. Why it is so is a fundamental question in the Architecture of

the Parthenon, and it will be addressed and explained in the next section, where and when the

derivation of the Parthenon’s skeletal structure is presented and analyzed.

On the basis of the above estimates and known lengths, it is suggested that the columns’

diameter is close to (but not exactly as long as) a fathom. The width of the Temple at the top of

the crepidoma (the stylobate) is close to (but not exactly equal to) a plethron; and the length of

the stylobate is close to (but not exactly equal to) 36 fathoms.

These quantities result in the following average inter-columnia (measured in the metric system):

narrow side, y’=1.90 meters and equal to the columns’ average diameter at their base, x being

an exogenously determined quantity in the system of equations (1); while in the long side, the

average inter-columnium is y”=2.16 meters. As presented first in the work by the author in [1.1],

the narrow side average inter-columnium y’ is smaller than the long side average inter-

columnium y”. This relationship, attributed mainly to Engineering Statics but also to Aesthetics

as discussed in [1.1], is fundamental in CGTs’ design and construction:

(y’ < y”). (2)

This is indeed a major aspect of CGTs Architecture, and a topic that has gone largely unnoticed in

the Literature, which focuses on measuring individual inter-columnia. We now turn to a closely

related subject, equally neglected and (due to the errors by Vitruvius) largely misrepresented in

the current literature on CGTs and in the Parthenon’s case as well.

The modulus and its grid.

Hence, we derive the average sizes M1 and M2 of the two-dimensional grid pattern’s unit of the

Parthenon’s floor plan modulus. The total (narrow sides) extent of the grid is seven times the

grid’s unit length, M1, along the East and West sides. Thus, we obtain at the narrow side: M1 =

(x + y’) = (1.90 + 1.90) = 3.80 meters, so that 7x3.80=26.60 meters (this length being .87 of a

ΠΛΕΘΡΟΝ). While, the equivalent dimension of the grid’s unit along the long (North and South)

sides is: M2 = (x + y”) = 4.06 meters, so that 16x4.06=64.98 meters. This comes close to 2.1 times

the length of a ΠΛΕΘΡΟΝ but not exactly twice it. Consequently, here we have clear confirmation

of our hypothesis, that these sides of the modulus (and by extension the sides of the stylobate)

were not constructed according to this or any other unit of length. They were rather derivatives

of other considerations.

20

In [1.1] the author, due to their closeness, rounded up these two counts to an almost 4-meter

square grid pattern modulus, which was an approximation to their estimated average sizes M1

and M2. This study, in that regard, slightly adds to the previous work by the author. In [1.1] the

author estimated the vertical dimension of the Parthenon’s modulus M3 to be also about 4

meters, where it actuality is close to 4.16 meters, so that the Parthenon’s columns average height

of 10.40 meters is approximately 2.6 times a four-meter M3. Hence, the 3-d modulus of the

Parthenon is approximately a cube with side lengths of about four meters, and applied in ratios

M1:M2:M3 as 1:1:2.5 in average modular units, a result roughly confirmed by this analysis

although slightly refined, where we found that the modulus dimensional ratios are exactly (in

meters) 3.80:4.06:4.16, and the relationship to hold:

M1 < M2 < M3. (3)

The reasons why these (otherwise unexplained) discrepancies in the 3-d modular grid average

unit sizes exist will become clear in a bit. In addition, the 4-meter 2-d modulus (grid average unit

size) of the Parthenon is close but again not identical to two fathoms (3.70 meters versus an

actual 3.80-meter modulus narrow side). On the long side of the 2-d modulus (4.06 meters) the

closest one comes to an ancient Greek unit of measurement (multiple or fraction) is the pace (2.5

paces to be exact). However, it is highly unlikely that two different units of measuring lengths

were used to form the 2-d horizontal surface part of the Parthenon’s modulus. Thus, again, the

rationale of a different way these Temple average sizes (x, y’ and y”) were arrived at (as it will be

presented in the penultimate section of this paper) looms as a far more likely scenario.

Earlier we encountered the modular units’ ratio R’, where the unweighted by their average actual

lengths modular units, 7 (along the narrow sides) and 16 (along the long sides), were employed

to derive it. Now we shall weigh these variables by their actual (estimated) average lengths,

M1=3.80 meters and M2=4.06 meters respectively. The modified R” is now given by the

expression:

R” = (16x4.06)/(7x3.80) = 2.4421

This of course is the cotangent of the angle (BAC) from Figure 2, its tangent being .3914. An angle

’ with tan=.3914 is (from trigonometric Tables) equal to ’=21.375. Angle ’ is the core angle

used in the previous subsection to derive the orientation of axis AC towards the Summer Solstice

sunrise. As the estimation of this angle is based on an estimation of the 2-d modulus’ average

grid it involves approximations which might be too rough. A more direct (and thus slightly more

accurate) estimation of this core angle will be supplied later in the text (next sub-section). Thus,

to derive the rectangle containing the floor plan of the Parthenon and its 46 columns at its

peristyle one needs just (the located at some point in space) point A; the direction towards the

sunrise at Summer Solstice; the length of the line AC; and the core angle ’. These two quantities

(given point A) are necessary and sufficient to generate the Parthenon’s rectangular base, the

stylobate, on which the columns of the peristyle are set. One may argue that two items of

21

information are also needed to draw a rectangle the conventional way: length and width, plus a

predetermined (corner) point and orientation.

However, here we were able to also obtain a specific reason as to why the particular orientation

of the Parthenon (off by an otherwise unexplained 10 to the North of the due East-West axis)

was selected. Location of the corner point could be related to other (exogenous) factors, possibly

having to do with the physical morphology of the site at the top of the Athens Acropolis; the

possible presence of a prior Temple at the site; and the relationships sought to govern the

location of the Parthenon in reference to other Acropolis structures. One of these factors

apparently had something to do with shadows cast by the Parthenon and other edifices at the

Acropolis, as presented and discussed in reference [1.1]). Thus, the reader must note that here

the information regarding the direction of the monument was endogenous to the analysis, and

not exogenous. By solving the system of equations in (1), if the columns’ diameter at their base

x is known, then the inter-columnia (for both the narrow, y’, and long, y”, sides) are directly

derived. In a more general formulation, where x is also an unknown, one can endogenously also

obtain the columns’ diameter at their base. But for that to be accomplished, one needs a broader

framework – the subject of a later section of this paper.

North-Western view of the Parthenon. Shadows and the various roles shadows played in the

location, as well as the functions of the Temple was discussed in [1.1]. ΕΝΤΑΣΙΣ and its connection

to the shadows cast by the entablature upon the Parthenon’s columns was discussed, offering a

novel explanation and rationale for its purpose and effects. Source of photo: [2.14].

22

The Parthenon’s Skeleton: Its Three Key Triangles and Core Angles

Figure 2. The Parthenon’s skeleton in a 45 axonometric diagram showing the Temple’s basic

Geometry, and the three key triangles in its structure (schematically, not in scale). Point H is the

Parthenon’s barycenter and omphalos. Line HH1 is the intersection of two of the skeleton’s three

key triangles, (CAD) and (FEG). Point H2 is the two triangles’ intersection line extended on the

surface of triangle (FEG) till it crosses line EG. The three key right triangles and their core angles

are: key triangle (BAC) and its core angle BAC (angle ); key triangle (CAD) and its core angle CAD

(angle z); and key triangle (FEG) with core angle FEG (angle ω). Source of diagram, the author.

The Parthenon’s key triangle (BAC) and its core angle .

We now return to the system of equations in (1). Before we provide the non-linear version of this

complex system of equations involving three variables (x, y’, and y”), an independent check will

be provided on the magnitude of angle ’. Previously, an estimate of ’ was derived on the basis

of the 3-d modulus. Now it will be derived directly from the sizes of lines AB and BC of the

Parthenon’s skeleton. Obviously, and given the L1 and L2 as given in the previous section,

AB=66.8-1.90=64.9 meters; and BC=28.5-1.90=26.60 meters (the columns’ diameter x being 1.90

meters). The above triangular specifications of the right angle (ABC), as shown in the 45

axonometric diagram of Figure 2, result in a hypotenuse AC=70.23 meters and an angle BAC =

= 22.3. Difference in and ’ is due to estimation errors, and can be disregarded. In the analysis

that follows the 22.3 angle size will be employed. Its tangent is tan = 26.60/64.9=.40986.

23

24

Figure 3. The Parthenon’s floor plan, source [2.4]. The orientation of the floor plan’s axis of

symmetry EF and the axis AC (a key axis in this paper’s analysis) are shown, with the direction of

the North at the upper left-hand side of the diagram. The orientation of the AC axis is towards

the rising sunrays at Summer Solstice to the East -Northeast, and towards the last glim rays of

the Winter Solstice at the West-Southwest. Length and width of the crepidoma (ΚΡΗΠΙΔΩΜΑ) in

meters are also indicated. Source of the final diagram: the author.

This is a core angle in the triangle (ABC), since the length of AC and precisely specify it.

Moreover, a 22.5 angle is exactly one sixteenth of 360, and the angle (22.3) is extremely

close to this angle size. This relationship is of extreme import (hint: the 22.5 angle can be easily

drawn with just a compass and a ruler, and is a good starting value in the search for an optimum,

the 22.3 value) in the formation of the skeletal structure of the Parthenon. Its import will be

further analyzed and highlighted in the last section of the paper, where the heuristics involved in

finding the optimal configuration of the Temple will be exposed.

What is of course of import is the convergence to AC=70 meters. This represents a ratio of about

1:12.5 as the hypotenuse of the 2-d modular structure is: d=5.56 meters. Before we look at the

other two key right triangles in the Parthenon’s skeletal structure which involve the Parthenon’s

columns height and its height including the pediment at its entablature, a few remarks are

necessary to address at this point the problem of the design specifications of the Classical Greek

Temples in 2-d. These are introductory remarks to a fuller exposition of this central topic to this

paper, to be offered in the paper’s penultimate section.

The Parthenon’s skeletal specifications problem.

Let us now review the system of equations in (1). It was assumed there that the total number of

columns (46 in an 8x17 arrangement), the columns’ average diameters (x), and the total length

of the stylobate’s 2-d dimensions L1 and L2 are known (exogenously supplied) parameters.

However, for the designer of the Temple, these are not exogenously supplied parameters, but

variables the values of which the designer and engineer of the Temple is supposed to derive. It is

precisely this type of questions we are set to address now more in depth, to the extent that the

Parthenon is concerned. Are there any clues or any systematic procedure that can be set up to

arrive at and answer the question of “how did the architects, Callicratis and Ictinos, settle on the

configurations we currently record” on this classical of all Classical Greek Temples.

Of course, Engineering and Statics had a lot to do with these variables; however, here on the

architectural and purely mathematical (Geometry and Algebra related) aspects of these variables

will be the focus. The original system of equations in (1) must be re-written in full as follows and

in a nonlinear form:

25

T1x + (T1 - 1)y’ = L1; T2x + (T2 – 1)y” = L2 (4)

where T1 is the number of columns at the narrow sides, in the Parthenon’s case, 8, and T2 is the

number of columns along the long side, in this case 17. Variables x, y’ and y” as well as L1 and L2

are as defined in the analysis surrounding conditions (1) – (3). The first three variables are

expressed in their averages. System in (4) is a second-degree nonlinear system of two equations

(plus the seven positivity conditions) with seven unknowns. It is noted, that among the seven

unknown variables, T1 and T2 must be in addition to positive also integers. Obviously, the system

is undetermined, which means that there must be other conditions to be supplied for it to have

a set of finite solutions. Due to its nonlinearity, these solutions may or may not be unique.

Mathematical Optimization Theory and the CGT problem.

It is obvious then, that other considerations must be introduced, for the system to obtain

endogenously derived solutions, and not be forced to have solutions by decreasing its degrees of

freedom, by arbitrarily (and exogenously) specifying some of its variables. How to do this

efficiently, is what this effort is all about. Moreover, we kept the design specifications of the cella

and its interior configuration (interior columns and walls, and their specific morphology) out of

this analysis, to simplify it. Adding the cella specifications (and following up from the analysis

involving the seven ratios in reference [1.1]) could provide avenues to address this set of issues.

What is pursued here now, in an effort to address the question of determining a Temple’s

morphological specifications as the outcome of an endogenous calculus, is to detect the

embedded instructions linking the three key right triangles and their core angle, as shown in the

design of the Parthenon’s skeleton of Figure 2. It is reminded that for a right angle to be specified

the length of any side and a core (one of the two non-90 angle) or one of its trigonometric

specifications (sine, cosine, tangent or cotangent) are needed.

In the mathematical Theory of Optimization, the information needed to obtain values of a

system of variables where the number of variables exceeds the number of equations available

(in effect, the number of constraints) is obtained through the system’s objective function. In that

case, the optimization process (either by maximizing or minimizing the value of the objective

function subject to the available constraints, hence optimally deriving values for the variables

involved) provides the means to solving the system of variables by the first (and appropriate

second) order conditions, in accordance with standard Theory of Optimization, see for example

[2.11]. Standard Theory of Optimization (which will not be reviewed here, the interested reader

can consult any reference from the very rich literature on this branch of Mathematics) affords

the derivation of the dual formulation of a primal objective function. This platform and problem

structure offer rich insights, as it points to the inherent dual nature of Optimization (involving

both maxima and minima). This is a very promising avenue of research in the statement of the

CGT problem of condition (4). This effort, towards an efficient approach to solving the Classical

Greek Temple optimization problem, will be more formally addressed in the following section.

26

The Parthenon’s key right triangle (CAD) and its core angle z.

From the previous section, the value of diagonal line AC is used (AC=70 meters) along with the

height of the Parthenon’s columns (10.40 meters) for key right triangle (CAD). This combination

of the main components of this key triangle results in the core angle CAD = z = 8.45 and a

hypotenuse, see Figure 2, of length AD=70.77 meters. Its tangent is: tan z=10.40/70=.14857.

The Parthenon’s key right triangle (FEG) and its core angle ω.

Now we examine the other key right triangle of Parthenon’s skeletal structure, seen in Figure 2,

triangle (FEG). The dimensions of this right triangle are, long side EF=64.90 meters, and FG=17.3

meters, see [1.1]. On that basis, one derives the length of the hypotenuse EG= 67.14 meters, and

the core angle FEG = ω = 14.85. The tangent of this angle is: tan ω=17.21/64.90=.26518.

Figure 4. Parthenon’s Southern corner of the entablature’s Eastern pediment. The estimated

about 13 (12.7 to be exact) basis angle of the Parthenon’s pediment (formed by the ΣΙΜΑ

framing the ΤΥΜΠΑΝΟΝ) is shown above. It is the place where the architects ΚΑΛΛΙΚΡΑΤΗΣ and

ΙΚΤΙΝΟΣ embedded one of the constituent angles of the Temple. Source of photo: public domain.

27

The Parthenon’s pediment angle

It is noted that the angle found on the Parthenon’s pediment, see Figure 4, is close to 12.7. It is

the angle formed by the sima (ΣΙΜΑ) at the two bottom corners of the tympanum (ΤΥΜΠΑΝΟΝ),

at the pediment’s structure. The angle at the top of the pediment is about 154.6. This result is

directly derived from the Parthenon’s façade reconstruction, shown in Figure 3.4, p. 35, in

reference [1.1], among a number of other reconstructions available in the literature, see for

example that outlined in [2.7] and [2.8] the reconstruction of the West pediment shown in Figure

5. In this reconstruction, the top angle of the pediment is about 155, directly implying that the

two base angles of the tympanum triangle are about 12.5.

Furthermore, this result is confirmed by the line CD of Figure 2, which coincides to a great extent

in the 45 axonometric with the righthand side line of the Temple’s pediment skeletal structure

(at the point of the Parthenon’s North-East corner column’s center). The geometric proof of this

is left to the interested reader to confirm. The pediment angle is about 10 less than the angle

(22.3). By examining a number of reconstructions (some shown in this paper) the author

estimates the tangent of the pediment’s angle to be about .22564, corresponding to an angle of

about 12.71.

Figure 5. Parthenon, West pediment reconstruction from reference [2.8].

It is apparent that these three core angles of the three key right angles (8.45, 14.85, 22.3) and

the 12.7 pediment angle are critically linked and intrinsically related to the instructions resulting

in the Parthenon’ skeletal morphology. How is that set of instructions embedded into the

Temple’s overall form, resulting in the pediment angles is the subject of the section that follows.

28

Three Lemmas and two Comments: three angles as the building blocks of the Parthenon

Lemma 1: the key ratio. As a consequence of analysis in [1.1] it was estimated that the total

height of the Parthenon (including the entablature) is 17.20 meters; see the relevant estimates

at p. 35 in [1.1]. With this analysis, one derives now that the ratio of lengths HH1 to H1H2 is

exactly 1.5. This is trivially obtained by the simple geometric property that: since HH1=10.40/2,

and HH2=17.30/2, then HH1/(HH2-HH1) = 5.20/3.465 = 1.5. Point H of course is the omphalos of

the monument as already pointed out. The 1.5 ratio is central, as it will be shown in the last sub-

section of the penultimate section of the paper. It deals with a heuristic based search for the

optimum solution of the optimization problem underlying the Parthenon’s skeletal morphology.

Lemma 2: the efficiency conditions. The three key triangles with their three core angles, three

variables in all, plus the information that they are of the “right triangle” type and that two of

these key triangles intersect at the barycenter H, plus the location of point A and the

astronomical orientation based direction of axis AC, are the necessary and sufficient conditions

to uniquely define the Parthenon’s skeletal structure in situ. Additional information concerning

the Parthenon modulus, is in an optimization process that can generate the number of columns

on each side of the peristyle, and the length, width and height measurements of the Temple.

Comment 1. In effect, the above algorithmic process is a holistic approach to precisely specify

both the location and orientation of the Temple, and optimally define the Parthenon’s skeletal

morphology, as it will be further shown by Lemma 3 and the following section of the paper.

Lemma 3: the instructions. The instruction on angles is derived by directly comparing the three

core ones, 8.45, 14.85 and 22.3 and connect them to the pediment angle of about 12.7. A

number of possible sequences (scenarios) can be drawn to generate these three-angle

measurements. A possible sequence (although by no means unique) is the following: use the core

CAB angle, , of 22.3, which is approximately one sixteenth of 360, as the base core angle;

subtract from the base core angle 8 (1/32 of 360) to obtain a (gross) approximation to the core

FEG angle, ω, of 14.85; subtract from the base core angle 10 to obtain an approximation to the

pediment’s angle (12.7); and finally subtract 14 from the base core angle to derive an

approximation to the core CAD angle, z, of 8.45. Thus, all four angles are linked to a base core

angle (=22.3) and to differences in even steps (14, 10, 8). Comment 2. Hence, the

proposition is put forward and the thesis is advanced in this paper that the Parthenon’s building

blocks were three core angles that can be generated as a sequence (subtracting 14 and 8

correspondingly) from a base core angle – which is the sixteenth of 360. At the very center of

this sequence of the three core angles (and the result of their meshing in forming the Parthenon’s

skeletal frame) is the pediment’s angle 12.7. it is thus concluded that a set of instructions on

angles is responsible for the Parthenon’s skeleton. Of course, numerous other sequences can be

found to generate these angles. Integrating the three key right triangles (containing the three

core angles) frames the specific morphology of the Parthenon’s skeleton of Figure 2. How this is

done critically hinges on the location of point H, the barycenter of the Parthenon’s floor plan.

The heuristic process involved is discussed next.

29

Stating the Parthenon’s Optimization Problem and its Heuristics

Introductory remarks: the Parthenon “genetic code” as a set of instructions

The exposition that follows can take two avenues to unfold. One is the geometrically based

avenue, in which the optimum configuration is attained by following a set of geometric

instructions. The other avenue is a Calculus based procedure. It produces the (same) optimum

values of the variables included in the Parthenon’s skeletal structure, except it does so

analytically, employing differential Calculus. To those familiar with the Mathematical Theory of

Optimization, this double approach to finding an optimum solution to an optimization problem

is also present in the (simple) case of Linear Programming. There, a set of (linear) constraints

bound the feasibility set; then the slope of the (linear) objective function is used to locate on (one

of) the feasibility frontier’s corners a (unique) solution, that is a point which maximizes the value

of the objective function subject to the set of constraints. This double in nature (but of course

identical in essence) procedure will be employed here to derive the optimal values of the

(geometrically in the form of a set of instructions and, at the same time, algebraically in the form

of a Calculus) stated variables (components) giving form to the Temple’s skeletal structure.

Of course, we have absolutely no evidence that 5th century BC Athens (even at its Golden Age)

and its mathematicians, astronomers, architects and engineers were in possession of the types

of Mathematics found in the contemporary mathematical Theory of Optimization. They were

also not familiar with modern Genetics, where in the DNA structure (the genetic code of living

organisms) as we now understand it, a set of instructions are embedded that are responsible for

generating the living organism’s morphology and internal structure. To them, the “instructions”

embedded in the mathematical specifications of the Parthenon’s modulus and overall

morphology were in all likelihood intuitively derived. The geometric procedures they followed in

effect were a substitute for searching for the optima of an optimization process regarding

Parthenon’s form. These geometric procedures, that involved the modulus and the key right

triangles and their core angles, will be exposed now, alongside the Calculus based procedures.

It is justified to assert that the emphasis by the Parthenon’s architects was on the geometric

instructions for creating a structure with angles (and right triangles) of the type discussed in the

previous section going through point H, the barycenter of the Temple and its omphalos, while

the Temple was anchored at point A with an orientation (line AC) towards the sunrise rays at

Summer Solstice. These angles present a mathematical (geometric in this case) sequence. That

sequence resulted in the unique solution which is manifested by the Temple’s specific

morphological configuration. This configuration is translated into a specific number of columns

(46), arranged in a configuration of 8x17 column peristyle, with specific (and differing) inter-

columnia, and the Temple’s length, width and height. All that information is contained in the

Parthenon’s skeletal structure morphology as shown in Figure 2.

30

Angles , z, and ω are by themselves and in combination of the existence and geometric

properties of point H, sufficient to geometrically define the (unique) 3-d skeletal structure of the

Parthenon. The ensuing specifications involving its 46 columns and crepidoma’s length and width

as well as the columns’ height and the pediment’s height are algebraically derived once the

geometric structure of the Parthenon’s skeleton is set. To do so, one need translate the

aforementioned angles (by computing their tangents) into quantities involving lengths, of course.

In other words, we need to state the necessary and sufficient conditions in terms of these

variables by the way of core angles of key right triangles, for one to derive from the skeletal

geometric structure, schematically shown in Figure 2, the algebraic (and differential Calculus)

conditions of the system in (4). Doing so requires that the angles , z, and ω be derived and be

drawn by means of a compass and a ruler (the only means available back then to doing

Geometry). It turns out that these three angles are produced by a set of instructions, with a

starting value as their base an easily defined and drawn angle, the core angle of triangle (BAC) –

angle . This angle is very close to one sixteenth of 360 (22.5). The other two angles (z=8.45

and ω=14.85) are a bit more complicated. Their derivation, and the architects’ ability to draw

them, requires an iterative method to be discussed shortly. In that iterative algorithmic

procedure, the embedded instructions are followed in a step-by-step schema. Before we do so,

however, a few notes are needed.

Two Notes

Point G (see Figure 2) is now (for simplicity) the top point of the Parthenon’s pediments without

accounting for the height of the top – middle – acroterion (ΑΚΡΩΤΗΡΙΟΝ) showing above the

pediment’s sima (ΣΙΜΑ) framing its tympanum (ΤΥΜΠΑΝΟΝ).

According to this analysis of the Parthenon, and in effect of all CGTs, there are some variables

(elements of the Parthenon or any other CGT’s Architecture) that are included in the skeletal

structure. They weigh more than others in a Temple’s construction. Here, the suggested

hierarchical import of the architectonic elements discussed (having to do with a Temple’s

location, orientation, floor plan and elevation) are superior in importance than the detailed sizes

of the various sub-elements of the structure, such as the steps of the crepidoma, or the various

sizes of the different components of the columns’ capitals, or the entablature’s elements (frieze,

metopes, triglyphs, etc.) This does not necessarily imply that these second-tier components of a

Classical Greek Temple are not important – in fact some of these elements and their dimensions

are in effect time markers assisting us now on how to date the approximate construction phase

of the Temple and even identify its architect(s) and sculptors. Moreover, their advanced

mathematical sophistication in their detailed configuration is also a time marker in the Evolution

of Form, Architecture, Engineering and Mathematics. Meticulous attention to detail is a hallmark

of Advanced and sophisticated Architecture, and certainly this is the case involving the

Parthenon.

31

The translation of angles into concrete variables of the CGT optimization problem

In this sub-section, the basic (skeletal) Geometry of the Parthenon, and its embedded geometric

instructions will be presented. The three core angles of the three key right triangles can be

translated as follows, so that the full optimization problem’s constraints (or a priori conditions)

are fully deployed in the form of a differential Calculus, as it will be subsequently shown. The

geometric instructions must correspond to the set of conditions found in the 2-equation system

(4), plus the positivity and integer conditions as stated earlier.

On top of these positivity and integer conditions, one must assume (exogenous) upper and lower

bounds, since the (integer) number of columns can’t be less or greater than certain limits. These

limits can be statistically derived, by inspecting the currently available records of CGTs. It is

reasonable to assume that a minimum of six and a maximum of nine are the columns

encountered in the narrow sides of a CGT, while a minimum of ten and a maximum of twenty are

encountered at its long side.

Hence, in addition to the two conditions in (4), one must also assume the following conditions

also to hold on the variable T1 and T2. Upper and lower bounds are not necessarily hard bounds

(either for the case of the Parthenon or any other CGT) as other upper and lower limits can be

tested in the geometric solution, and the differential Calculus based search for an optimum

solution to be discussed following the Geometry based solution. Hence one has:

6 < T1 < 9 , 10 < T2 < 20. (5)

Or stated differently, in an Integer Programming form, these variables can only obtain one of the

values in the vectors:

T1 = [6, 7, 8, 9]’ T2 = [10, 11,...,19, 20]’. (5.1)

Of course, these are suggestions (indeed, weak assumptions) as already stated. In the case of the

Parthenon, how the solution regarding the peristyle’s colonnades (that is the optima) involved:

T1* = 8, and T2* = 17. (6)

will be demonstrated next.

Optimum values for variables T1 and T2 (designated as T1* and T2*) and the optimal average

values of variables x, y’ and y’’ (designated as x*, y’*, y”*) given the conditions in system (4) and

the constraints in (5.1) emerge as the geometric solution to the problem of “fitting” or “meshing”

the three key right triangles from the three core angles CAB, that is angle (the base angle of

the entire system, and about one sixteenth of 360, that is 22.5, and with tan = BF/AB), CAD,

that is angle z (8.45, with tan z=CD/AC) and GEF, that is angle ω (14.9, with tan ω=FG/EF).

The columns’ ratio R (17/8=2.125), with the four corner columns being counted twice, and the

(unweighted) modulus grid ratio R’ (16/7=2.2857…) are values derived from this geometric

solution, a consequence of the two lines AC and EF intersecting at point H and the two key

32

triangles (CAD) and (FEG) intersecting at line HH1 under the relationship (see Lemma 1 of the

previous section) linking line segment HH1 to H1H2 (responsible for the exact ratio of 1.5), as

shown in Figure 2 and proved in Lemma 1. The ensuing modulus is the outcome of this

(heuristically derived) geometric structure of the Parthenon’s skeletal structure. The step-by-step

procedure is as follows.

The step-by-step heuristic derivation of the Parthenon’s skeletal structure and orientation

We now present the systematic search for the optimum configuration of the Parthenon’s skeletal

structure, shown in Figure 2. It follows a heuristic method in its Geometry (the Calculus from the

nonlinear optimization process will be outlined later in this section). This process is necessary, as

the exact drawing of the basic angles z, and ω can’t be done employing just a compass and a

ruler, due to the fractions they contain. The keys in this procedure is the closeness to the angle

22.5 by (22.3, and how it is approached by successive approximations) and the stopping rule

of attaining the exact ratio of 1.5 between the HH1 to H1H2 line segments.

Step One: Set point A on the Acropolis site plan, an exogenous decision.

Step Two: Set the line AC, oriented towards the sunrise of the Summer Solstice on the one hand,

and towards the sunset of the Winter Solstice on the other end. Note: point C will be derived at

a following step of this search process.

Step Three: At point A draw a line AB at an angle approximately equal to 22.3. For example,

an initial value of 22.5, an angle BAC which is exactly one sixteenth of 360 and can be easily

drawn, can be a good proxy (starting value). Note: location of point B will be derived in a later

step.

Step Four: At point A and on a plane perpendicular to the ground intersecting it at line AC, draw

a line forming an angle CAD equal to 8.45 (angle z). Starting at a 9 is a good starting value, as a

9 angle is precisely one fortieth of 360. Note: point D will be located by a later step.

Step Five: At point A draw a line AE perpendicular to AB towards the North-Northwest. Note:

The decision to form a rectangular Temple skeletal 2-d structure is exogenous to the above

described process. Note: point E will be derived from an iterative procedure (and this constitutes

part of the heuristic aspect of the optimization process).

Step Six: At line AE, on the plane perpendicular to the ground, and from any point E draw a line

forming an angle FEG equal to 14.85 (angle ω). Starting at a 15 (1/24 of 360) is a good starting

value, as it was the case for step four and angle z. The two planes containing angles ω and z

intersect (designate that line as HH1). Point H on the ground is the barycenter of the 2-d schema

of the Parthenon’s skeletal structure and its 2-d modular grid. Points F and G will be derived from

a later step.

33

Step Seven: At a distance from point E on the AE line, mark point E’ (note: E’ is not designated

on the diagram of Figure 2) such that AE=EE’.

Step Eight: At point E’ draw a line E’C perpendicular to AE (hence, perpendicular to AE’ at E’), a

line which is also parallel to line AB. This line intersects the AC line at point C. Note: this is how

point C is obtained on line AC drawn earlier at step 2; furthermore, the intersection of line AC

and the vertical to the ground line CD at point C is how point D on the plane containing triangle

(CAD) is arrived at from step 4, and this key right triangle (CAD) is formed. Finally, point B from

step 3 is also defined, thus forming the key right triangle (ABC).

Step Nine: On the plane vertical to the ground and containing line CD, draw a plane parallel to

line AE’ (which is also then vertical to the line AB at point B). This defines points F and G from

step six, and thus the key right triangle (EFG). It also identifies point H2 on the HH1 line, this being

the intersection of the two key right triangles (ACD) and (EFG).

Step Ten: Compute the ratio HH1/H1H2. If different than 1.5 (a critical value obtained from the

previous section) then repeat search process from step 3.

Heuristics, the Parthenon and the CGTs

The step-by-step process presented above applies to the specific case of the Parthenon’s skeletal

structure. However, under appropriate modifications it might apply to other CGTs as well. It

contains in toto four loops: the first and longest loop is between steps 3 and 10 (it adjusts the

size of angle with a very good starting value at 22.5); a second loop is between steps 4 and 10

(it adjusts the angle z); a third loop is between steps 6 and 10 (it adjusts the angle ω); a fourth

loop is between steps 7 and 10 (it adjusts for the magnitude of line segment AE). Step 8 makes

simply an accounting of whether the three key right triangles are formed; and step nine computes

the magnitude of the resulting critical ratio and its deviation from the exact value (1.5). In this

heuristic process, the stopping rule involves the formation of the key right triangles and the

arrival to the ratio of 1.5. Within this ratio, the conditions set (integer total number of columns

and their partition into T1=8 and T2=17) and the quantities of x, y’ and y” are obtained. These

quantities are obtained thus, because numbers 17 and 8 are the only integer numbers which

precisely and perfectly subdivide the line segments AC and BC.

Steps 1 to 10 listed above outline a qualitatively equivalent heuristic process of locating an

optimum within the constrained set (and on the feasibility frontier) of a Linear Programming

problem. In this case, things are a bit more complicated, because it is a Nonlinear Programming

problem we are confronting. Magnitudes of changes in the heuristic procedure sketched, and the

direction of change are fine points in need of further analysis, not to be supplied here. Hence, we

arrive at a conclusion demonstrating how a set of instructions on angles involving a sequence of

steps in the meshing of three key right triangles generate the modular structure (and grid) of this

Classical Greek Temple’s skeletal morphology.

34

But this optimal values can be obtained as well by appropriately solving a Calculus based

optimization problem, the possible nature of which and the meaning of its objective function are

topics to be pondered next.

The CGTs Objective Function: Primal (Harmony) and its Dual (Costs)

We are now set to head-on confront the core argument of this paper: that the Parthenon, as an

architectonic structure, was the outcome of an optimization process, the morphological result

of a heuristic algorithm partly embedded in a sequence built into the Temple’s skeletal structure

(its key right triangles, their core angles and their links as discussed earlier in the text of the

previous sections and especially the prior sub-section), that produced the various components of

the structure as optimal solutions to a problem in optimization. We suggest an interpretation of

this objective function: the maximizing of a harmonious coexistence among the Parthenon’s

various sizes of all the elements (number of columns, their average thickness, and their average

inter-columnia) of the Parthenon’s sophisticated skeletal structure and modulus. This syllogism

implies that the objective function is an Aesthetics driven function. Employing averages in the

optimization function, aggregate analysis can be carried out. However, various classes of these

variables can be explicitly recognized. In which case, the optimization problem acquires a

disaggregate form. For purposes of illustration, the aggregate analysis case will be shown below.

Parametric specifications of the objective function contain within them trade-offs. These

parameters weigh the importance of the various state variables (reflecting the concrete

morphology of the Temple) as to their relative contribution to the value of the objective function.

The objective function is optimized subject to constraints. Next, we analyze the form of these

constraints, conditions reflecting the Parthenon’s overall (albeit skeletal) morphology.

In conditions (4) and (6), where (4) is a generalization of (1), the constraints of the optimization

problem were set, plus the positivity conditions on x, y’ and y” and the integer conditions in (5):

0 < x, y’, y” (7).

Again, the location of the anchor point A (an exogenous decision, possibly related to a prior

Temple on this site), and the orientation of the axis AC (an endogenous decision in the overall

process outlined here, but possibly associated with the prior Temple as well, and where its angle

to the due East-West orientation is an endogenous variable to the specific problem of

optimization) are given as specified earlier. Now the focus is exclusively on the optimization

problem’s objective function involving the following set of variables: x, y’, y”, T1, T2, L1, L2. These

are the seven state primal variables involved in a primal objective function, where all seven are

linked so as to maximize the harmonious relationship simultaneously among them all.

In abstract, the general primal objective function stated as to maximize Harmony can be

written as:

35

Maximize = F{x, y’, y”, T1, T2, L1, L2} (8)

subject to the constraints in (4), (5), (6) and (7). By substituting the values of L1 and L2 from

conditions (4) into , one has the transformed objective function ’:

Maximize ’ = F’{x, y’, y”, T1, T2}. (8’)

This is an objective function on five unknowns (state primal variables), subject only to positivity

conditions in (7), regarding the state variables x, y’, and y” and the integer conditions regarding

T1 and T2 found in (5). Of course, through T1 and T2, the R and R’ enter the objective function,

and thus, all considerations brought up in prior sections about Number Theory and Mathematical

Sequences become of essence.

The specific, nonlinear, parametric and algebraic form of is of course subject to differing

formulations, which will not be further elaborated here, as they involve mathematical aspects far

beyond the objectives of this paper. But speculation as to the possible (and quite likely)

interpretation of this -function is appropriate at this point. It is of little doubt that Harmony

among the Parthenon’s components, and through them the projection of Harmony in human

relationships, was a critical issue of import at that time, manifesting itself in both Art and

Architecture, as well as in Athenian society and its broader culture during Pericles’ Golden Age.

Harmony can be argued to be present in the face of structures embedding relationships such as

the Golden Ratio, or the Ratios found in other irrational numbers (such as the Silver Ratio and ).

Such Ratios have played a role in the overall design specifications as well as in the details of

edifices (Temples and other private as well as public buildings). They have been detected in the

design of artifacts of the time. Is it possible that some of these Ratios were involved in the -

function? This remains an open question, and a subject for future research.

Given the known Parthenon skeletal form, one can work backwards, deriving the Parthenon’s

original design objective function, by analyzing the Optimization Problem’s first order conditions.

These conditions require the first partial derivative of the Lagrangian function L, a function which

includes and a set of five Lagrange multipliers (the vector ’, associated with the primal

formulation’s set of five constraints), with respect to each primal state variable to be set to zero:

L = - 1C1 - 2C2 - iDi (9)

L/x = 0, L/y’ = 0, L/y” = 0, L/T1 = 0, and L/T2 = 0 (10)

where L is the Lagrangian objective function; and the vector ’ are the five Lagrange multipliers

(and dual variables) associated with constraints C1 and C2, these two being the two integer

requirements associate with the number of the peristyle’s columns in the narrow and long sides

correspondingly; and iDi are the Lagrange multipliers i(i=1,2,3) associated with the three

positivity conditions of variable x, y’ and y” respectively. The vector of the multipliers ’ is in

effect the vector of the Optimization Problem’s dual variables.

36

Equations in (10) provide the necessary conditions for optimality. Sufficiency is met by the second

order conditions associated with the optimization problem. Since the primal objective function

is maximized, the second order conditions (the second derivatives) must be negative. For a

standard introductory reference to this and associated issues in the Theory of Optimization, the

reader is directed to reference [2.11], which has a nice exposition of the economic aspects

involved here as well. Economics are of essence, since architectural construction is the subject.

In deriving the full form of the primal objective function , and thus the form of its Lagrangian L,

we need to also revisit the Number Theory aspects of the numbering involved with the 46

columns of the Parthenon’s peristyle discussed earlier, and we will also revisit the number N1=32,

and N2=55. We shall also touch upon the nature of the ratios R and R’. In so doing we will revisit

the discussion on the embedded sequence.

One might be willing to speculate that the optimization problem, i.e., to maximize subject to

the stated constraints, entails a quantity and a function in which the product of these numbers

(or a nonlinear parametric function of them), N1 and N2, R and R’, must be involved as well. In

this case, part of the objective is to create a set of column numbers (along the narrow and long

sides of a Temple) such that their product is maximized, always subject to the constraints stated.

These constraints guarantee that the three resulting main right triangles produce core angles as

specified. Of course, the solution to this integer (due to T1 and T2 being integers) optimization

problem is also heuristically derived as indicated previously, and being reflected in the

geometrical configuration of the Parthenon’s skeletal structure, provided in Figure 2.

It is widely accepted that Classical Greece was the place and time that Harmony entered the Arts

and Architecture. Interpreting in detail and elaborating on the notion of “harmony” isn’t of

course the subject of this paper. This is a complex notion, subjected to multiple interpretations

and culturally determined formulations over millennia. But in essence, what is offered here is a

concrete method in which this complex, abstract and largely qualitative notion acquires a

quantitative representation. The primal objective function (which incorporates all the

aforementioned variables, comprising the Parthenon’s skeletal structure and modulus) can be

aptly interpreted as an expression of Harmony. The constituent elements are nothing but the

components of this Harmonious coexistence at the optimal value of the composite objective

function. However, this is by no means the only interpretation one might be motivated to attach

to this primal objective function ; others may suggest different interpretations, which might be

at least equally appealing interpretations. This task is left to the interested reader to ponder.

Before concluding this exposition, let us briefly elaborate on the dual formulation of this Theory

of Nonlinear Integer Optimization Problem, since this aspect of the Theory of Optimization is

critical in fully understanding what is involved in the optimization process. The dual objective

function, to be designated here as is of course to be minimized subject to the equivalent dual

constraints. As is well known in the Theory of Optimization, at optimum, * = * (that is, the

maximum of the primal equals the minimum of the dual – if the primal objective function is to be

37

maximized, conversely if the primal objective function is to be minimized, then the dual objective

function is to be maximized).

Moreover, the Lagrange multipliers that are in effect the dual variables of the dual formulation

(associated with the dual constraints) are the primal variables. Another critical condition linking

the primal and dual formulations at optimum is that the product of the primal variable at

optimum times the corresponding dual constraint be zero; and the product of the dual variable

at optimum times the corresponding primal constraint be zero as well. Let’s briefly address what

might be the interpretation of the dual objective function .

In the field of Economics, see [2.11], the standard interpretation of the dual of a primal

maximizing objective function dealing with tangible quantities, is that they (the dual variables, in

this case the array of ’), represent the real ‘economic cost” or “opportunity cost” or “real

economic rent” of the primal quantities entering the primal objective function. In the case of

stating the dual of a primal objective function in the optimization process involving CGTs, the

likely interpretation of the dual variables (the Lagrange multipliers corresponding to the primal

set of constraints) is that they represent bundled (or “comprehensive”) engineering and

economics related costs embedded in a dual function that the designer wishes to minimize. This

is a suggested interpretation, but other interpretations are also plausible.

Instructions, the skeletal structure and the modulus: some thoughts.

A clue as to the presence of an optimization process at work, what in contemporary parlance is

referred to as a heuristic algorithm in search of an optimum solution to a Theory of Optimization

type problem, is a dep seated paradox that surrounds the Parthenon. Given that the architects

of the Parthenon paid extraordinary attention to detail, one would expect to record

measurements of its structural components that are exact fractions or multiples of known to

exist at the time units of measuring lengths, areas, volumes etc. Yet the actual sizes of certain

basic elements of the Parthenon like its façade’s length or the length of the Southern side, or the

columns’ height, do not seem to be either exact multiple or exact fractions of known units of

measurement used back then.

The fact that none of the actual (as estimated at present) features-components of the Parthenon

exactly fit any of the known ancient units of measuring length, area or volume, as indicated in an

earlier section of the paper, or at least they do not do so in a consistent manner, might be an

indication of two things: first, that these components’ lengths were the result of the optimization

process (or instructions sequence resulting in some configuration) which produced the geometric

form of the Parthenon’s skeleton as shown in Figure 2; and second, that deep inside the

Parthenon’s structure, there are some key components (found in its skeletal morphology) which

are exact and beyond any approximation and accuracy of measurements doubts in their

derivations. In fact, we located two of them. They were related to angle - an angle linked to the

38

Parthenon’s orientation; and to the ratio 1.5, linked to the Temple’s barycenter in its 2-d floor

plan, where the featured attraction of the Parthenon was located, the statue of Athena.

Basic features of the Parthenon, namely elements (T1, T2, R and R’) of the Parthenon structure,

as well as x, y’, and y”, were not the initial elements of the design process, but the consequence

of some other more primordial and fundamental design considerations. They were in effect the

outcome of a heuristic process involving a set of fundamental instructions embedded in the

formation of the Parthenon’s skeletal morphology. Put differently, the Parthenon’s 7x16 2-d

modulus and also the modulus in its unfolding in 3-d sizes, were the outcome of the more basic

instructions involved in meshing the three key right triangles and their three core angles to form

the skeletal outline of the Temple as shown in the author’s diagram of Figure 2.

One step in these instructions was the derivation of the angle shown at the Parthenon’s two

pediments, the Southern corner of the Eastern pediment shown in Figure 4. The various

discrepancies observed between the actual components and the fractions or multiples of various

ancient Greek units measuring lengths are due to the formation of the structure obeying these

instructions. The exact replication of the three core angles and the pediment’s angle of Figure 4

are evidence that these triangles, angles and instructions were the starting steps of the design

process, whereby the final skeletal form was heuristically derived.

To this heuristic one may also attribute the differentials among columns’ diameters, and inter-

columnia. An exact replication of the currently observed individual column dimensions and inter-

columnium would require a powerful computing, based on parallel processing procedures to use.

Whether this parallel processing would be able to precisely replicate the current Parthenon

morphology at a level of approximation leaving no reasonable doubt is itself doubtful. It could be

that the architectonic production process that resulted in the Parthenon as it now stands (in all

the minute details) is not possible to reproduce, being a unique type of experiment (route

towards solution, in a nonlinear optimization problem) in the search for an optimum.

Going back to the point, regarding our inability (or failure) to replicate specific elements of the

Parthenon’s Architecture by using Ancient Greece type units of length, as evidence that deeper

quantities (associated with the skeletal structure of the Temple, angles and ratios and on

objective function largely responsible for these observed lengths) one may also reasonably

counter-argue that the differences we record between the exact fractions or multiples of the

various units of measuring lengths available to the architects and engineers at the time of

Classical Greece and its Golden Age, i.e., to the architects ΚΑΛΛΙΚΡΑΤΗΣ and ΙΚΤΙΝΟΣ, and the

actual components of the Parthenon as we have them today and measure them, may also be the

result of the weathering over the millennia of these Pentelic marble elements of the Temple; as

well as the humanly caused destruction the Parthenon experienced over time. However, it is

suggested here that the main factor is not the latter, but rather the former.

Earlier, and by this analysis, the author rejected the competing hypothesis that the cause of all

these discrepancies was due to the possibility that the architects built the Parthenon not on the

39

basis of a blueprint but on an improvising, unplanned mode. To the contrary, the findings here

supply evidence that a very careful and sophisticated sketch plan, involving a set of instructions

on angles plus a core and important ratio, were behind the construction of this Temple.

Primitive Pythagorean Triples and the Parthenon’s Triangles

Before concluding this study, it would had been imprudent if one were not to check whether the

three key right triangles of the Parthenon’s skeletal structure, as well as half of the triangle

embedded at the Temple’s pediments (shown in part in Figure 4) are in fact Primitive

Pythagorean Triples (PPTs). The author demonstrated in his paper on Le Grand Menec monument

of standing stones at Carnac, Brittany (see reference [1.4]), that a tradition in monumental

Architecture may have existed, even prior to Pythagoras, that could possibly entail at least some

knowledge and potentially some minimum understanding of PPTs since the 5th millennium BC.

Hence, quite likely in a post Pythagoras world of Mathematics in 5th century BC Classical Greece,

the implanting in monumental structures of some key triangles from the hierarchical list

comprising the Tree of PPTs may had been underway, and thus it might be possible to detect

some of them, implanted in the structures of CGTs and quite likely in the case of the Parthenon,

at present. It is worthy thus asking the research question of whether any (or all) of these four

important right triangles (the three key ones and that at the pediments) of the Parthenon, that

were identified here and possibly other triangles found on the Parthenon’s various components,

are part of that list. In [1.4] links to some introductory references on the topic of PPTs are found,

for the interested reader. Their mathematical property is that the three sides’ length (measured

in modular units) of these right triangles are coprime.

Such a search entails a systematic (possibly computerized) examination of the candidate PPTs as

to how well they match these four key triangles of the Parthenon. Here, a rather rough approach

will be taken, whereby three possible PPTs will be tested as to how close they replicate these

four important Parthenon right triangles. In a, more or less, random search approach, two

attributes of the four Parthenon right triangles were compared to three PPTs chosen to be tested:

core angle, and length of the hypotenuse (expressed in modular units). It is recognized that the

search requires confirmed accuracy and excellent approximations to be available on the

Parthenon’s right triangles sides’ lengths and angles, for the conclusions to enjoy a high

confidence level. Hence, the same caveats apply as those stated earlier.

The three PPTs examined were: (7,24,25), (11,60,61), and (13,84,85). They were selected because

their hypotenuse is close to their long side – an attribute exhibited by the four Parthenon right

triangles, but especially triangles (CAB) and (FEG). In the three PPTs chosen to investigate, their

corresponding core angles are: 16.3, 10.4, and 8.8 respectively. It would seem then that the

only candidates for PPT is the right triangles (CAB) – possibly corresponding to PPT (13,84,85).

However, this topic needs further study, and of course better approximations to the actual sizes

of the three key triangles in the Parthenon’ skeletal structure and the pediments’ triangle.

40

Conclusions and Suggestions for Further Research

A number of conclusions can be drawn from the above analysis. First and foremost is the

conclusion that the Parthenon was built not on the basis of setting a priori the number of columns

and their split along narrow and long sides; or by pre-setting length and width measurements of

the Temple’s rectangular floor plan. Instead, it is established by the analysis provided that these

components of the Parthenon’s overall morphology were the result of a far more complex

algorithm (or a set of instructions) involving a process of optimization. This is not to imply that

the Parthenon’s architects ΚΑΛΛΙΚΡΑΤΗΣ and ΙΚΤΙΝΟΣ were familiar with either Genetics (the

DNA embedded sort of instructions) or the mathematical Theory of Optimization and its various

branches (including Integer Programming and Computing).

Apparently, they had a strong intuitive sense of the Heuristic Geometry based algorithmic

process involved in the search for optima (or satisficing conditions) in an optimization process.

Their intuition is to be appreciated in conjunction with their search for harmonic relationships

among the elements of the Classical Greek Temple. Their reliance on the angle (one sixteenth

of 360) and the exact ratio of 1.5 in the H1/H1H2 line segments at the barycenter (omphalos) of

the monument, where ΦΕΙΔΙΑΣ located his statue of ΑΘΗΝΑ ΠΑΡΘΕΝΟΣ, are architectonic

components one must marvel at and at least deeply appreciate. These two quantities were the

building blocks of the Parthenon’s skeletal (and possibly entire) structure’s unfolding in 3-d.

A major conclusion of this work is that the Parthenon (and possibly all Classical Greek Temples)

were built according to a heuristic mode in the search for an optimum solution. The optimality

condition was based on an objective function that was nothing else but a comprehensive

harmonious relationship linking all basic elements of the Parthenon’s (and possibly in the case of

all CGTs) skeletal structure. Maximizing this harmonic relationship embedding objective function,

subject to certain realism containing constraints on the number of columns in the Temple’s

peristyle, formed the framework within which the Parthenon (and quite possibly all CGTs) were

made.

The search involved central components of the Temple’s architectonic elements beyond the total

number of columns at its peristyle, like for example their ratio of splitting them into narrow

versus long sides’ colonnade, the Temple’s length, width and the columns’ height, etc. It could

be that the Parthenon, in this genre of architectonic construction of that Era (Athens’ Golden

Age), was an optimum optimorum type of solution. This will require a more elaborate research

effort involving a number of CGTs to confirm. In this regard, this paper can be viewed as having

setting up a program of research activity.

It was found that the basis of the Parthenon was three key right triangles, and their three core

angles. The building blocks of this basis were angle and the ratio 1.5, plus a set of instructions

governing the generation of the other two core angles in the Parthenon’s skeletal structure. In

this interplay among the three key triangles, the central role of the Temple’s barycenter and

omphalos of the monument was highlighted. A fourth angle, related to the core angles’

41

underlying instructions to build the Temple, was imprinted onto the Parthenon’s Eastern and

Western pediments.

Another conclusion derived here is that the split of a Temple’s 46 columns at its peristyle between

the narrow (8) and long (17) sides was a derivative decision tied (among other factors) to the

Number Theory aspects of the CGT’s colonnade. This is an area which requires also further

research.

Moreover, in the paper’s conclusions it must be noted that, the finding (first reported and

documented in a previous paper by the author) that the inter-columnium along the narrow side

(usually, although not always, this being the East and West sides of the Temple) is smaller than

the inter-columnium along the long side (usually, but not always, this being the North and South

sides) of the CGT was reconfirmed. The average inter-columnium along the narrow side y’ was

found to be equal to the average diameter x of the typical column at its base (y’=1.90 meters);

whereas the average inter-columnium along the long side (y”) was found to be 2.06 meters.

Finally, it was reconfirmed that the modulus of a CGT is the distance between the very center of

two neighboring columns; and that the Temple’s modulus length is the sum of an average

column’s diameter at its base on the stylobate plus the side’s average inter-columnium (x+y’, and

x+y”). On the average, it was also re-affirmed that the Parthenon’s 3-d modular grid was a cube

of approximately four meters in length on each side. The closest to this modular size (four meters)

any ancient Greek unit of measurement comes to is two fathoms (about 3.70 meters). Using the

Greek cubit, it would require about 8.79 of them to come close to the 4.06 meters modulus’ sides

length. It is abundantly clear that these Parthenon components were not derived using any of

these units.

All estimated measurements reported here, and the resulting relationships need to be confirmed

by other researchers. Before being admitted as evidence of the suggested optimization theory

based propositions put forward here as underlying the Parthenon’s design. This is usual scientific

practice, and it applies to all empirical studies. In this regard, this study is no exception. A more

refined exposition of the method proposed, involving closer approximations to the

measurements of the various Parthenon components, and especially those incorporating the

entasis effects of the structure, is a way to also extend and elaborate on the topics of this paper.

Two subjects of potential mathematical interest were brought up, as a result of analytically

approaching the Parthenon’s (and in fact all CGTs’) morphology and in particular its (and their)

colonnades. One had to do with Number Theory, the other with Mathematical Sequences. It is

expected that these two areas of investigation, sprung from the detailed analysis of these

Temples’ colonnades, might open up new areas of mathematical research.

42

Epilogue

There are numerous aspects of Architecture, Art and Engineering; of History and Culture; of

Economics, Politics and Religion; and of Mathematics of course, that this marvel of monumental

construction has stimulated writers and analysts, students and researchers in all these fields of

human endeavor to record, contemplate and upon which to reflect. A good summary is found in

[2.12].

It is neither astonishing nor surprising then, that this detailed view of the Parthenon’s skeletal

morphology evokes work in at least five additional fields of Mathematics, with interesting

findings added to its already well stocked arsenal of wonders: Mathematical Theory of

Optimization; Algorithmic Computing; Number Theory; Theory of Sequences; and the Theory of

Primitive Pythagorean Triples. To those, one might also add Statistics, a subject alluded to here

but not covered in any detail.

In simply addressing the Theory of Optimization part of this list of fields in Mathematics, one is

led to the suggestion that the Parthenon’s construction possibly attained the maximum

maximorum in its objective function, indicative of the accomplishment that was achieved, when

compared to that of any other Classical Greek Temple. This attainment might reveal the reason

why the Parthenon has been singled out as the pinnacle of Classical Greek Architecture within

this category of monumental construction, and possibly beyond it. Undoubtedly, a number of

additional areas of Mathematics are still awaiting work, to be fully employed in an ongoing effort

to fully gauge and grasp the Temple’s inner workings as well as its impact on the Human Heritage.

The Parthenon from a South-West view. Source: [2.13].

43

References

Author’s work

[1.1] Dimitrios S. Dendrinos, 10 April 2017, “Moving Shadows and the Temples of Classical

Greece”, academia.edu. The paper is found here:

https://www.academia.edu/32383784/Moving_Shadows_and_the_Temples_of_Classical_Gree

ce

[1.2] Dimitrios S. Dendrinos, 24 January 2017, “The Mathematics of Monoliths’ Shadows”,

academia.edu. The paper is found here:

https://www.academia.edu/31101997/The_Mathematics_of_Monoliths_Shadows

[1.3] Dimitrios S. Dendrinos, 7 April 2017, “The Dynamics of Shadows at and below the Tropic of

Cancer in the Northern Hemisphere”, academia.edu. The paper is found here:

https://www.academia.edu/32426535/The_Dynamics_of_Shadows_at_and_below_the_Tropic

_of_Cancer_in_the_Northern_Hemisphere_update_1

[1.4] Dimitrios S. Dendrinos, 21 November 2016, “A Carnac Conjecture: Neolithic

Experimentation with Primitive Pythagorean Triples?”, academia.edu. The paper is found here:

https://www.academia.edu/30163918/A_Carnac_Conjecture_Neolithic_experimentation_with

_primitive_Pythagorean_triples

[1.5] Dimitrios S. Dendrinos, December 1991, “Methods in Quantum Mechanics and the Socio-

Spatial World”, Socio-Spatial Dynamics, Vol.2, No.2: pp 81-108.

Work by others

[2.1] http://www.goddess-

athena.org/Museum/Temples/Parthenon/Parthenon_NW_from_NW_rec.html

[2.2] http://www.dvdtalk.com/reviews/33095/nova-secrets-of-the-parthenon/

[2.3] https://en.wikipedia.org/w/index.php?title=File%3AParthenon-top-view.svg

[2.4] By Io Herodotus - Own work, CC BY-SA 4.0,

https://commons.wikimedia.org/w/index.php?curid=56293415

[2.5] http://www.ancient.eu/parthenon/

[2.6] For an Introduction to Classical Greece units of measurement, see for example reference:

https://en.wikipedia.org/wiki/Ancient_Greek_units_of_measurement

44

[2.7] http://www.ancientgreece.com/s/Parthenon/

[2.8] http://www.newworldencyclopedia.org/entry/Parthenon

[2.9] https://www.britannica.com/topic/Parthenon

[2.10] http://ancient-greece.org/architecture/parthenon2.html

[2.11] Michael D. Intriligator, 1971, Mathematical Optimization and Economic Theory, Prentice

Hall, Englewood Cliffs, New Jersey.

[2.12] http://ancient-greece.org/architecture/parthenon.html

[2.13] http://www.ancient.eu/image/943/

[2.14] http://imgarcade.com/greek-architecture-parthenon.html

[2.15] http://www.metrum.org/key/athens/dimensions.htm

[2.16] https://oedipustheking.wordpress.com/what-oedipus-rex-tells-us-about-ancient-greece/

Acknowledgements

The author wishes to acknowledge the contributions made to his work by all of his Facebook

friends, and especially by the members of his twelve groups the author has created and is

currently administering. Their posts and comments have inspired him in his research over the

past two and three-quarter years.

But most important and dear to this author has been the almost 22 years of encouragement and

support he has received from his wife Catherine and their daughters Daphne-Iris and Alexia-

Artemis. For their continuing support, assistance, encouragement and understanding for all those

long hours he allotted doing research, when he could have shared his time with them, this author

will always be deeply appreciative and grateful. Special thanks, in addition, are due to my

daughter Daphne-Iris who assisted me in the trigonometric analysis of this paper.

Legal Notice

© The author, Dimitrios S. Dendrinos retains full legal copyrights to the contents of this paper.

Reproduction in any form, of parts or the whole of this paper, is prohibited without the explicit

and written permission and consent by the author, Dimitrios S. Dendrinos. Copyrights on photos

used not in the public domain belong to the sources cited. All diagrams produced in this paper

are individually and collectively copyrighted by the author. No individual diagram can be

reproduced without the author’s explicit permission and consent.

45