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Right now, in 2022, we can read with perfect understanding mathematical articles and books
written a century ago. It is indeed remarkable how the way we do mathematics has stabilised.
The difference between the mathematics of 1922 and 2022 is small compared to that between the mathematics of 1922 and 1822.
Looking beyond classical ZFC-based mathematics, a tremendous amount of effort has been put
into formalising all areas of mathematics within the framework of program-language implementations (for instance Coq, Agda) of the univalent extension of dependent type theory (homotopy type theory).
But Coq and Agda are complex programs which depend on other programs (OCaml and Haskell) and frameworks (for instance operating systems and C libraries) to function. In the future if we have new CPU architectures then
Coq and Agda would have to be compiled again. OCaml and Haskell would have to be compiled again.
Both software and operating systems are rapidly changing and have always been so. What is here today is deprecated tomorrow.
My question is: what guarantee do we have that the huge libraries of the current formal mathematics projects in Agda, Coq or other languages will still be relevant or even "runnable" (for instance type-checkable) without having to resort to emulators and computer archaeology 10, 20, 50 or 100 years from now ?
10 years from now will Agda be backwards compatible enough to still recognise
current Agda files ?
Have there been any organised efforts to guarantee permanent backward compatibility for all future versions of Agda and Coq ? Or OCaml and Haskell ?
Perhaps the formal mathematics project should be carried out within a meta-programing language, a simpler more abstract framework (with a uniform syntax) comprehensible at once to logicians, mathematicians and programers and which can be converted automatically into the latest version of Agda or Coq ?
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I just encountered a notification about this article on Mathematical Proofs and the value of Proof Assistants, https://www.ams.org/journals/notices/202401/rnoti-p79.pdf
I resonate most with the positions by Lamport (author of LaTex and a Turing Award Laureate) and Laurence Paulson (author of ML for the Working Programmer and working very much in proof assistants). I think it will be clear that the situation about the presentation of proofs and incorporation of such proofs in mathematical publication is still very much up in the air.
I also did a ResearchGate search on "Proof Assistant" and the fire-hose of articles confirmed my view that this is yet stabilizing, although there are extensive favorite approaches.
Here is the above paper's abstract:
“A proof is one of the most important concepts of mathematics. However, there is a striking difference between how a proof is defined in theory and how it is used in practice. This puts the unique status of mathematics as exact science into peril. Now may be the time to reconcile theory and practice, i.e., precision and intuition, through the advent of computer proof assistants. This used to be a topic for experts in specialized communities. However, mathematical proofs have become increasingly sophisticated, stretching the boundaries of what is humanly comprehensible, so that leading mathematicians have asked for formal verification of their proofs. At the same time, major theorems in mathematics have recently been computer-verified by people from outside of these communities, even by beginning students. This article investigates the different definitions of a proof, the gap between them, and possibilities to build bridges. It is written as a polemic or a collage by different members of the communities in mathematics and computer science at different stages of their careers, challenging well-known preconceptions and exploring new perspectives.”
There is already an objection to this material on the list where I found it. The objection is to this statement: "This puts the unique status of mathematics as exact science into peril.” That statement disturbs me too, but maybe not for the same reason.
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Let P(z) denote the (rational) transfer function of an nD system, where z=(z1,...,zn), of a spatial-temporal discrete recurrence Givone-Roesser type system or Fornasini-Marchesini type system. Assume that P(z)2=P(z) for any z as above.
1. Can we prove that P(z) is stable? meaning that all the P(z) entries have denominators with no zeros in the open polydisk D^n (assuming that in each entry n(z)/d(z) the numerator n(z) and the denominator d(z) are relatively prime).
2. Can we prove that is structurally stable? meaning that all the P(z) entries have denominators with no zeros in the closed polydisk (assuming that in each entry n(z)/d(z) the numerator n(z) and the denominator d(z) are relatively prime).
Many Thanks!
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Dear Peter!
Sorry! P(z) is the mxm transfer function of some nD Givone-Roesser type system or of some nD Fornasini-Marchesini type system, and z=(z1,z2,...,zn), with n at least 2.
I've already reported that the answer is "no" in general, unless m=1, where the problem is trivial.
But anyway, Many Thanks For Your Interest And Response!
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Dear friends
Thank you in advance for your help and collaboration. Here in my lab we are working on a photosynthetic plant and we have a non-linear subactuated bilinear model (attached image with the model). The u(t) (dilution rate), the two output variables are x1(biomass) and x3 (volume), alpha1,2 are positive constants and a1,2 are constants. E(t) is a bounded disturbance.
In this type of systems it is necessary to obtain a system in its canonical form (chain of integrators), to be able to propose a Sliding Mode array control?
How would you implement a sliding mode system in this type of systems?
Thank you in advance, if you are also interested in collaborating with the multidisciplinary working group, write to me at aerodriguez@conacyt.mx
Kind regards
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Why do you absolutely want to use sliding modes?
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My current research involves the impact of culverts on the distribution of a salamander species, and I am attempting to include road usage levels in the analysis. I cannot find any sources for good road use estimation methods.
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Travis,
This is an interesting question and one that I haven't really seen proposed anywhere. However, it does seem logical that "stream order" could be used to describe road usage, at least to some degree. You might be able to contact the department of transportation in your state and see if they have data on road usage from different "orders". They often collect this type of data when looking at widening roads, adding new stoplights, etc. So, any data they have and can share would allow you to look at possibly providing a proof of concept for this type of system.
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Google and other giant tech company has already introduced such types of system .
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Thanks for asking. Actually I am very beginner in image and vedio processing. But I actually want to make such an extension that not only protect porn related searching but also stop this kind of advertisement, also working with youtube, and that can be mantain by parents for childern and device will be save for them. Those which are already introduced work only to protect from searching which I have seen. So I think this will be a devolapment of this kind of software.
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Is it possible to derive the theoretical formulation for rotating cantilever beam as force is a function of rotating speed or displacement.
Suppose 1000 rpm applied, during rotation, the beam vibrating and deflects at some frequency.
Deflection is caused in the beam due to rotational motion, similar to deflection is caused in the beam due to tip excitation, base excitation(force relations are there for this excitation source and FEM simulation is also done for this type of system)
For rotational system, how can i apply a force as a function of rotational speed in the Finite Element Analysis
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You are welcome.
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Most countries have some type of system to forecast crops related information to the farmers. But most of time information are generic to the geographical region rather atmospheric regions. Hence many farmers loss their crops and investments due to unpredictable weather, soil, water and seeds compatibility and feasibility etc and inaccurate information due to no time-bound delivery of information.
In result, in the world, thousands and thousands of farmers are going for suicide every year. This is much bigger figure than majority of wards of the world.
Is artificial intelligence based adaptive mathematical model possible to quickly forecast best crops for the farmers every month and in case any drastic chance in weather soil or seeds, farmers should be able to go choose plan B to reduce the effects of surprises.
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This scenario has many critical measures and effect keeping usability and risk mitigation in mind. There are different types of farming, e.g. limited time serial farming where adult plants can be planted to harvest fresh and with quality like flowers, that needs prediction for month. similarly there are many use cases in this domain.
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PACS systems are nowadays ubiquotous in developed countries. However, quite often DICOM images can be seen in one institution only a and the ways to share these results between different institutions are limited to CD/DVD sharing.
Is there a cloud/mail/other type of system to share DICOM images in your country?
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Thanks all, sharing DICOM systems definitely differ a lot in various countries! That is why I want to get as much info as possible...
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There are many types of systems in the bacteriological laboratory are used for identification of bacteria Pseudomonas spp. which one is gratified.
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Both the systems are good for bacterial identification even if the Vitek system is better especially for environmental species; moreover you have to consider the cost that for ViteK is much higher than for the API system.
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Hi eyeryone,
I have problem to determine CMC in mixed type systems i mean :different ratio of concetration of cationic surfactants. I use a conductometric titration to measure it. But i cannot obtain any repeatable data. My compounds are quaternary ammonium salts with different alkyl chain length. I hope that someone has experience in that field.
Thanks in advance,
Marta
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what is the approximate difference of conductance values between the two different data sets. if the difference is small and the cmc values are similar then you can take average of different data sets.
usually we keep concentration of one surfactant fixed and titrate it with other surfactant ( micellar range ).
Usually CMC of such systems does not show any regular pattern but the conductance values are usually similar
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In the books "Energy Harvesting Systems" and "Piezoelectric Energy Harvesting" I have seen different models for the description of cantilever type systems. I would like someone to explain the differences to me, or advise me some article that talks about it.
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Single-Degree-of-Freedom (SDOF) electromagnetic generator model probably suitable for this purpose.
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to choose type of system for ammonia water
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Hi dear,
Thanks for the question.
The best absorber for ammonia is water. The Oldham's diagram is useful for this purpose (ammonia in cooling devices).
with my best wishes.
Adel OUESLATI
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Hello Researchers,
                                  I want to model natural filler or fiber molecular dynamics on polymer composites. Can I get any clue for modelling this type of system? what type of force field I can use.
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Since Java is included in that range, I'm curious about Scala.
Note that Scala is more difficult to analyze than Java for several reasons, including but not limited to:
- Compile-time code generation (e.g., macros)
- Expressive type system
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see lots of examples: http://spinroot.com/cobra/papers
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A non-minimum phase system is difficult to control because of RHP zeros. How to deal with this type of system?
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It is very hard to require among several zeros every zero be LHP. Therefore most of systems are non-minimum phase, and this proposed question is very important.
From root locus rules, the most obvious harm of RHL zeros is that high gain is prohibited, because high gain can make the closed poles reach these zeros.
This is why the asymptotic LTR of state space theory cannot be applied to non-minimum phase systems, because asymptotic LTR means asymptotic high gains.
However, using a simple state space technique described in my publications, an output feedback compensator (OFC) can be designed for systems either with more outputs than inputs or with at least one LHP zeros (the OFC poles will be assigned to match these LHP zeros).
This OFC is very general because it is equally very hard to have among several zeros every zero be RHP.
This OFC can estimate a number of linear transformations of system state (like a number of additional system outputs), while this number equals the OFC order. Thus a much improved static output feedback control can be designed. This form of control is a constrained state feedback control, which is by far the best form of feedback control.
This OFC has a distinct advantage than normal observers. The exact LTR or full realization of robustness of state feedback control, is achieved by OFC.
This OFC fully utilizes the LHP zeros by matching them with the OFC poles, while avoiding the harms of RHP zeros by not requiring high gains at all.
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Hi everybody,
How can I design a back stepping controller for this system? h1 and h2 are states of the system and q is the input.
Because, in Khalil's book, design is said for specific type of systems.
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Your system is not smooth enough for backstepping design if you want to stabilize the system to the origin.  But, due to the structure of the system may exist if one considers only 0 \leq h_2 \leq h_1 region in the state space.  (The system is only well defined in that region.)  Now, change the coordinates to (x_1,x_2) = (h_2,h_1 - h_2) and use x_1 as the output, q as the input, and x_2 as the virtual control input.  Remember that x_1 and x_2 are both nonnegative and you don't have full control authority in the stabilization of x_1 dynamics.  But, x_1 will go to zero if x_2 is zero.  So, set the virtual control law x_2 = 0 and continue to the second step of backstepping, where you have full control authority with input q.  Try this to see the result.  
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The optimal control of hybrid photovoltaic/thermal systems is complex due to the opposite optimal operation points of the two separated systems.
In fact, to increase the efficiency of a photovoltaic module is needed to decrease its temperature, whereas to increase the efficiency of the thermal part is necessary to increase the temperature of the fluid (in our case water). Of course the control variable can be the flow rate of the water, but the range of variation of the flow rate is quite narrow. I would like to contact researchers that work experimentally on this subject.
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Dear Dr. Tina,
i've been working for a system integrator company in the central east coast of italy. We developed a solution for a PVT panel and i tried to model and control the prototype.
I used a non linear economic target function and an heuristic optimization (hill climbing method with fuzzy logic)
attached a preliminary version of the paper published in the IECON 2013 proceedings...
i hope it will be useful...
best regards
Lucio