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boarders.bsky.social

@boarders.bsky.social
1.1K followers 2.5K following 4.2K posts

Thanks to impermanence all things are possible Working on a book on topos theory

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boarders.bsky.social @boarders.bsky.social · 25m
you win the award for the person I most expect on here to be reading a biology book by a biologist who happens to know homology and cat theory
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boarders.bsky.social @boarders.bsky.social · 28m
👀
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boarders.bsky.social @boarders.bsky.social · 47m
I strongly dislike the semantic under-determinism of what a commit message or commit history should be -- should it be some kind of rationally re-constructed series of design decisions, or should be be a historical account of development -- and I rather resent it as a halfway house of neither
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boarders.bsky.social @boarders.bsky.social · 51m
the current victory of connectionist/historicist methodologies over rationalist methodologies and who supports each story is really fascinating if you are a sicko
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boarders.bsky.social @boarders.bsky.social · 52m
but I recognize people will have radically different experiences, and really can be way closer to one end or the other in the kinds of things they work on and think about
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boarders.bsky.social @boarders.bsky.social · 52m
in software of the sort I do, there is a constant push and pull between these dynamics and some of the fun of the discipline to me is to try to figure out what is mathematics, and what parts are computational/empirical and how can I get the two to best interact
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boarders.bsky.social @boarders.bsky.social · 54m
which involves a kludge of many different interlocking systems and insights which we use to constrain the computational world in various ways we learn how to, but which in no way comes close to a formal mathematical specification of anything
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boarders.bsky.social @boarders.bsky.social · 54m
in my way of thinking, wherever we can get formal mathematical models of something we should cherish that as a crown jewel e.g. compcert giving a compiler which has a formal semantics of C is an incredible achievement, but we what we are doing is often closer to 'modelling the weather system'
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boarders.bsky.social @boarders.bsky.social · 56m
I wouldn't quite say it like that, we should hold onto and cherish as much as we can about the formal thing at the heart of something, and then accept the bitter lesson of computation that we don't have a formal mathematical model of the entire scenario
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boarders.bsky.social @boarders.bsky.social · 1h
On the other hand, one aspect of any engineering discipline is how one designs for fault/precision tolerance, and it really often misleads us to think all of our systems are anything close to formal semantics compared to something closer to empirical object with constraints
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boarders.bsky.social @boarders.bsky.social · 1h
I agree with that, but I will say that a compiler has something at least approaching a formal mathematical theory of what correctness might mean, and I think that must be part of the consideration with how one thinks about these things
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boarders.bsky.social @boarders.bsky.social · 1h
W
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boarders.bsky.social @boarders.bsky.social · 1h
I remember being young and getting morphine in a hospital and my dad telling me it is chemically essentially the same as heroin and that radically re-shaping how I thought about drugs, addiction, the I'd been misled into believing about drugs creating instant and permanent chemical dependence etc.
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boarders.bsky.social @boarders.bsky.social · 1h
she seems one of the democrats who is better able to adapt to a changing environment (not sure I would have predicted that, but it does seem to be the case)
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boarders.bsky.social @boarders.bsky.social · 1h
W
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boarders.bsky.social @boarders.bsky.social · 2h
how about programs that call a relational database, how about differences in arithmetic semantics, or in the under-determination of specs (IEEE floating point, json etc.), how about how they handle timing and branching (which is observable behaviour to a cryptographic program!) etc etc etc.
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boarders.bsky.social @boarders.bsky.social · 2h
100% agree and I think it is shocking how much people don't think about how complex observational equivalence of programs really can be. Some examples include: when are these two programs that use rng the same, how about concurrency
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boarders.bsky.social @boarders.bsky.social · 2h
lmao
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boarders.bsky.social @boarders.bsky.social · 3h
“wealth creation”
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boarders.bsky.social @boarders.bsky.social · 4h
it’s the cope that kills you
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boarders.bsky.social @boarders.bsky.social · 4h
what I don't understand is I am sure one could have many uses for using it to enhance lecture notes e.g. turning markdown notes to latex, help with tikz diagrams, asking about the correct logical ordering to put certain material (perhaps) etc. but writing the actual course material? huh??
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boarders.bsky.social @boarders.bsky.social · 4h
The above clay institute document defines in mathematical terms what ‘physically reasonable’ means and the openAI solution satisfies those purely mathematical conditions
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boarders.bsky.social @boarders.bsky.social · 4h
and what does that document define "physically reasonable" to mean?
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boarders.bsky.social @boarders.bsky.social · 4h
if the openAI paper (which I am sure is atrociously written) claims that, then that is not great as a piece of scientific communication, but it has no bearing on whether they solved one variant of the NS problem, which they did
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boarders.bsky.social @boarders.bsky.social · 5h
I think about this image and the one about the banker who can say slurs against disabled people again way too often
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boarders.bsky.social @boarders.bsky.social · 5h
It is like stating you haven't solved the poincaré conjecture because what we _really_ care about is the smooth poincaré conjecture
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boarders.bsky.social @boarders.bsky.social · 5h
I will just say that mathematicians all the time care about these kinds of distinctions (smooth vs real analytic) and many problems are secretly regimes of different problem types, but the idea that one counts as having solved a clearly stated problem and the other doesn't is nonsense
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boarders.bsky.social @boarders.bsky.social · 5h
I'd be happy to know any source that gave you this impression
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boarders.bsky.social @boarders.bsky.social · 5h
I know for a fact that mathematicians as a whole don't think this or agree with you, but I want to know if what you are saying is based on anything according to you
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boarders.bsky.social @boarders.bsky.social · 5h
can you provide a single paper or even source of any kind which backs up the claim that the millennium problems were specifically only about a physically meaningful or possible input?
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boarders.bsky.social @boarders.bsky.social · 5h
I agree we won't do human rewrites, I just think almost all of the work of rewrites is moved towards verification, and most people will need some slightly compelling reason to want to do that sort of verification compared to the many other things they have to do
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boarders.bsky.social @boarders.bsky.social · 5h
Ah got it, I think constantly re-writing code will be a waste of agent's time, it seems to me they are better off writing provably correct transpilers or something higher value than acting as intergalactic translators
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boarders.bsky.social @boarders.bsky.social · 5h
if I have a large and complex codebase, then I would like various core components to be highly trustworthy with good boundaries. Until the point one has a specification for synthesizing the exact code and interfaces, I wouldn't want to just rewrite it for lack of belief that I can trust the outcome
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boarders.bsky.social @boarders.bsky.social · 5h
I don't fully follow how that answers what I've said
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boarders.bsky.social @boarders.bsky.social · 5h
it is very recent, and I regret to inform you this was all vibe-coded: github.com/leanprover/c...
github.com
GitHub - leanprover/con-leche: An external lean checker with a proof of consistency
An external lean checker with a proof of consistency - leanprover/con-leche
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boarders.bsky.social @boarders.bsky.social · 5h
worth saying that the lean kernel goes way beyond implementing the type theory in carneiro's thesis, so this is a different source of issues which is that people would like lean to be expressive enough for complicated constructs, but this comes into conflict with whether what is implemented is sound
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boarders.bsky.social @boarders.bsky.social · 5h
I am sure the cost or rewrites is going to plummet, but I think this seems like a big waste of time, and based on some fallacy that if the agent does it then it comes at no cost. Surely we will have better things to do with our time (and agent's time) than constantly doing huge rewrites?
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boarders.bsky.social @boarders.bsky.social · 5h
and actually all of the above should be ZFC + inaccessible cardianals / grothendieck universes (I wrote ZFC+ for it in the last post)
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boarders.bsky.social @boarders.bsky.social · 5h
didn't capture all the features that the lean kernel implements. Recently the lean team wrote a new kernel in lean itself which proves that the type theory has a model in ZFC+. This is, of course, circular so only shows lean is sound if you believe the proof doesn't use some unsound feature of lean
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boarders.bsky.social @boarders.bsky.social · 5h
It depends on the type theory, martin-löf dependent type theory (or variants like homotopy type theory/cubical type theory) have models in set theory and so are sound wrt ZFC. The type theory of lean had a proof due to Mario Carneiro that it had a model in ZFC, but the proof was incorrect, and /...
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boarders.bsky.social @boarders.bsky.social · 7h
a related example is Quine's new foundations: en.wikipedia.org/wiki/New_Fou... which has had controversy over its soundness since it existed
en.wikipedia.org
New Foundations - Wikipedia
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boarders.bsky.social @boarders.bsky.social · 7h
and those aspects are not well understood. It is actually very analogous to adding a new axiom to ZFC (or several) and wondering if what you get is still consistent with ZFC
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boarders.bsky.social @boarders.bsky.social · 7h
well apologies if so, but your questions don't clarify it, why would it make a difference that ZFC doesn't have contradictions compared with an implementation of a type theory? The rules that cause the contradiction are subtle aspects of the theory (e.g. the type theory of nested inductives)
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boarders.bsky.social @boarders.bsky.social · 7h
universes and it was incorrect. For your second point, because one can draw a contradiction from the rules of the logic, it doesn't mean it will be easy, it can be just as hard as any counter-example in mathematics
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boarders.bsky.social @boarders.bsky.social · 7h
yes, so it may be hard to construct a formal model in ZFC set theory (e.g. can one construct a model for ZFC + CH, well yes but that is a hard theorem of Godel) for all of the rules which end up being complicated (e.g. there was an original proof that lean has a model in ZFC + grothendieck /...
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boarders.bsky.social @boarders.bsky.social · 7h
this was exploiting a bug in the kernel (actually two different bugs in two different kernels iirc)
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boarders.bsky.social @boarders.bsky.social · 7h
How do you imagine an ordinary proof of soundness or unsoundness of a logic looks?
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boarders.bsky.social @boarders.bsky.social · 9h
this is why I like to write R[x,y] as R[x,x] since they are both definitionally equal
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boarders.bsky.social @boarders.bsky.social · 9h
anthropologists: curiously, humans have been anatomically modern for around 200,000 years but are only thought to have developed what we would identify as modern behaviour around 50,000 years ago with what is thought to be the emergence of language. I wonder why it took so long?
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boarders.bsky.social @boarders.bsky.social · 9h
important in itself. But it it perfectly plausible to me that many skills are not particularly useful at all (I currently have llms handling nearly 100% of my merge conflicts completely autonomously and I am happy to wave the white flag).
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