Geoffrey C. Shephard’s research while affiliated with University of East Anglia and other places

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Publications (25)


Is Selfduality Involutory?
  • Article

October 1988

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8 Reads

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12 Citations

Branko Grünbaum

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G. C. Shephard







Analogues for Tilings of Kotzig'S Theorem on Minimal Weights of Edges

December 1982

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18 Reads

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36 Citations

North-Holland Mathematics Studies

This chapter discusses analogues for the tilings of Kotzig's theorem on minimal weights of edges. For any edge E in a graph G, the weight w(E) is defined to be the sum of the valences of the two vertices at the ends of E. The weight of G is defined to be the least value of w(E) for all edges E in G. The theorem of Kotzig states that the graph of vertices and edges of every convex polyhedron (3-polytope) has weight 13 or less. The chapter discusses analogous results for plane tilings. By a (plane) tiling ү = {Ti |i ∊ I} a family of plane sets Ti is meant, called the “tiles” of ү, which covers the plane without gaps or overlaps. The union of the sets Ti is the whole plane, the interiors of the tiles are pairwise disjoint, and each tile is a closed topological disk. With each tiling ү an infinite graph is associated, “the graph of ү,” which has as vertices the one-point intersections of two or more tiles, and as edges the arcs common to pairs of tiles; tiles which have a common edge are said to be adjacent. The chapter presents a figure on tilling in which each vertex has valence 7 and hence each edge has weight 14.




Citations (14)


... A tiling or tessellation is a set of regular polygons which are isometric and cover the entire manifold without overlappings or voids. In the Euclidean case there exist exactly three isometric tilings, which are the well-known square, triangular and honeycomb lattices [93]. The corresponding characteristic lattice spacing h can be scaled freely. ...

Reference:

HYPERTILING — a high performance Python library for the generation and visualization of hyperbolic lattices
Tilings by Regular Polygons
  • Citing Article
  • November 1977

Mathematics Magazine

... us is the scheme developed by them [56] that allows us to generate an isonemal weave pattern with two simple operations: (1) create a random binary matrix (M ) called the fundamental block and (2) repeat/tile the fundamental block in the Euclidean plane. In this construction, M can be visualized as a square grid with a cell being either black (0) or white (1). ...

Satins and Twills: An Introduction to the Geometry of Fabrics
  • Citing Article
  • May 1980

Mathematics Magazine

... A configuration may have more than one self-duality maps (in our case we have altogether 6, as we have seen above), thus the following definition makes sense. The rank r(C) of a self-dual configuration C is the minimum value of r(δ) over all self-duality maps δ of C. (We note that this notion was introduced by Grünbaum and Shephard [18] in case of geometric objects for which self-duality can be defined, in particular, for polyhedra and configurations; for further details related to configurations, see [16] and the references therein). ...

Is Selfduality Involutory?
  • Citing Article
  • October 1988

... There exists extensive literature on fabric construction and mathematics. The classic work of Grunbaum and Shephard [4][5][6][7] pioneered research into which periodic weaves are isonemal. Fabrics that are not isonemal are not really fabrics at all, as a set of warp and weft threads (that are themselves mutually interwoven) can lift off from the rest. ...

Isonemal Fabrics
  • Citing Article
  • January 1988

... An interesting description of homogeneous polyhedra can be found in [14,15] (more general results for homogeneous polytopes in multidimensional Euclidean spaces can be found also in [16]). Another description of homogeneous polyhedra follows from the classification of all tilings on the 2-sphere with natural transitivity properties [8]. Here we collect some useful results on the structure of homogeneous polyhedra in order to study more narrow classes. ...

Spherical Tilings with Transitivity Properties
  • Citing Article
  • January 1981

... In the two adjoining chapters he also describes several with more than one kind of regular polygon as faces. In the 1979 paper by Grünbaum and Shephard [19], the beginnings of the application of incidence symbols to infinite collections of polygons in periodic surfaces in 3-dimensional the electronic journal of combinatorics 16 (2009), #R22 space were described. This was one of the ingredients that led to the enumeration approaches of the present paper. ...

Incidence symbols and their applications
  • Citing Article
  • January 1979

... Figure 6 shows two patterns with overlapping motifs that cannot be distinguished by the base types in [4]. An extension to the catalogue of 1-sided periodic pattern types that allows patterns with intersecting or disconnected motifs can be found in [3]; the base types in Table 3 that contain a hyphen refer to this list. ...

Tilings, patterns, fabrics and related topics in discrete geometry
  • Citing Article
  • January 1983

Jahresbericht der Deutschen Mathematiker-Vereinigung

... The mentioned result was developed in various directions. In the case of toroidal graphs the weight is at most 15, see Grünbaum and Shephard [6]. Zaks [16] and Ivančo [9] analysed the weight of graphs embedded in orientable surfaces of a positive genus, while Jendrol' and Tuhársky [12] were interested by weights of graphs embedded in non-orientable surfaces. ...

Analogues for Tilings of Kotzig'S Theorem on Minimal Weights of Edges
  • Citing Article
  • December 1982

North-Holland Mathematics Studies