The Eternal Doorman

Yesterday while listening to Tim Maudlin:  Physics and Physical Phenomena  I was struck by his idea that ( 1:40:09 ) he found he could do a path-counting procedure on 2+1 dimensional spacetime and recover an invariant that appeared like a relativistic interval.  Google go to great lengths to prevent people from accessing the text of the transcripts: See On the Emergence of Both Relativistic Structure and a Global Foliation from Discrete Space-Time .  I wondered why this didn't automatically apply to 3+1 dimensional spacetime too. I guess because he imagines a pre-existing lattice of some kind and the combinatorics are unmanageable. My thought was that maybe something like this would work inside a procedure which was effectively a completion process on a measure space as well. This would not have occurred to Maudlin because he's a realist! See  David Albert Talking Complete Nonsense . I found the above ERC talk he did on 2022: Subscribe to  PROTEUS And here ...

I had in idea about this whilst listening to this interview with Bernhard Schröder and Bernhard Fisseni : See their Natural language Proof Checking project  https://naproche-net.github.io/ : The Naproche system is an implementation of the ideas developed by the Naproche project. It accepts a controlled but rich subset of ordinary mathematical language including TeX-style typeset formulas and transforms them into formal statements. Linguistic techniques are adapted to allow for common grammatical constructs and to extract mathematically relevant implicit information about hypotheses and conclusions. Finally, automated theorem provers are used to prove the correctness of the input text.   42:20  Listening to this discussion around creating shared facts by locutionary acts it occurred to me that in a sense the idea of frames is partly psycho-linguistic and partly social. So I started to wonder whether there were any ancient Greek words which were to do with the idea of sha...

You would think these were more or less the same thing, ... but that's not true. 1:21:25 On what is a good theory and on space and time. See  The Category Enriched over the Category of Finite Sets, The Finitely Triangulated Manifold and the Magnitude of a Finite Category . My  comment : 21:52 I have been watching Dr Jorge Diaz's videos about the early history of Quantum Mechanics and it is clear from these that what they started with were indeed bona fide physical phenomena, reported in terms of drawings of spectrographs and things. Then the Quantum Theories were put forward, but these theories included 'entities' such as the spin states of free electrons. These things were not physical phenomena, they were part of the theory proposed to underlie the physical phenomena such as Zeeman splitting. So the theory was able to progress in terms of abstract, imaginary properties of physical systems with no clear idea of how or even whether any physical ...

This is absolutely brilliant, and there are lot's of great puns about burgery! My comment:   12:42 No you can't keep your secret things there because that belongs to the CIA. Subscribe to Luke O'Sullivan .

Not many people know who Emil Post was, but his model of computational processes as generating systems is one of the simplest to understand. It sits somewhere between the combinator calculus of Curry and Schönfinkel and Church's Lambda Calculus . See Geoffrey K. Pullum's  Creation myths of generative grammar and the mathematics of [Chomsky's] Syntactic Structures . Post proved his Normal Form Theorem for Post canonical systems which shows that "Given any Post canonical system on an alphabet A , a Post canonical system in normal form can be constructed from it, possibly enlarging the alphabet, such that the set of words involving only letters of A that are generated by the normal-form system is exactly the set of words generated by the original system" . What this shows is that a Post canonical system which generates a language can be abbreviated by adding non-terminal symbols which allow sub-structures to be reused at multiple places, thus potentially ...

I'm quite impressed by Frank Pfenning's Adjoint Functional Language he described at OPLSS'24 . It's a language based on Linear Logic with a co-monadic structure which is a kind of modality with associated adjoints which allow a shift from structural to substructural logics in the types. See  https://www.cs.cmu.edu/~fp/projects.html#adjoint  for details. Subscribe to OPLSS'24 . Both he and Bob Harper are funded by Jane Street . See  Bob Harper's Course on Principles of Programming Languages  and  Frank Pfenning's Course on Linear Logic . Most of what programmers do with general purpose programming languages is only done because of what other people do, and those things are almost always done only because of other things other people have done, and so on and so forth. So the benefits of being able to compose programs from the top-down are quite significant. See How Could One Unify CMU and MIT .  We are heck of a long way from being able to manage the te...

She says you can't cheat the physical laws like conservation of energy. Why not? Will God get angry? Subscribe to Charlotte Moser . Physicists cheat laws of physics all the time. It's the way you do physics: you observe an equation then you infer a mechanism that is behind it that somehow causes it to hold. Some people think this is the basis for all of reality: see A New Kind of Science . See his 2020 paper  Quantised Inertia and Galaxy Rotation from Information Theory . Subscribe to Mike McCulloch .

See  Orbifold notation .  Subscribe to  Istrail Laboratory . 

I mean, how to get the best of the two different philosophies of computation. One is based on typed programming languages and the other on engineering with diagrams . This is about practical computing and the cost and feasibility of software development in general. Here is the problem: We have a lot of algorithms which can all be described abstractly using some sort of pseudocode, or perhaps using some particular language (usually Python!). These algorithms are often well-studied and a lot is known about them in terms of their computational complexity in time and space. Substantive practical software systems invariably employ many such algorithms, often implemented in libraries with more or less well-specified APIs. But very few of these libraries are capable of interoperating because they are either packages written in some specific programming language like Java or Haskell, say, or they are written in C and used as object code, or they are written in an interpreted language like Sc...