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Unanswered Questions

160 questions with no upvoted or accepted answers
22 votes
0 answers
564 views

Categorical semantics of Agda

I would like to know the state of the art regarding the categorical semantics of the type theory implemented by Agda — or at least some approximation of that type theory that is amenable to ...
20 votes
0 answers
233 views

What is known about performance bottlenecks in proof assistants?

Background In my personal experience, the biggest bottleneck to broader adoption of proof assistants (in industry and mathematics) is the effort it takes to engineer proofs. (In lines of code, for ...
20 votes
0 answers
275 views

Can we automatically get around set-theoretic difficulties?

One of the main technical annoyances of working with (large) categories is the variety of set-theoretic difficulties that come about with it: if we use ZFC as background logic, then those large ...
15 votes
0 answers
211 views

Code generation from Locales and Sublocales in Isabelle

Problem Description I stumbled on this limitation/misunderstanding several times when using locales and sublocales in Isabelle. As a minimal example, let us extend the locale from the example in ...
13 votes
0 answers
368 views

Unintentionally proven false theorem with type-in-type outside logic and foundations?

We are all familiar with Russell's paradox, and it is known that Per Martin-Löf proved that type-in-type is normalizing and consistent (which is false), by accidentally using an assumption in his meta-...
13 votes
0 answers
564 views

How to speed up Lean?

I've recently been writing my first somewhat serious proof in Lean. While doing that, I noticed that Lean gets slower very fast with increasing length of the proof (slower in the sense that whenever I ...
12 votes
0 answers
168 views

Rules for mutual inductive/coinductive types

Some proof assistants, like Agda and maybe Coq, allow families of mutually defined types, or nested definitions of types, in which some are inductive and others are coinductive. I have no idea what ...
12 votes
0 answers
197 views

Do any automated theorem provers have the ability to stop, save state, reboot computer, restore state, continue?

With automated theorem provers knowing ahead of time how long the search will take or even if it will find a solution is unknown. Often for long running searches one eventually just has to halt the ...
10 votes
0 answers
187 views

Is there a proof assistant (or an embedding) for the (co)end calculus?

A Higher-Order Calculus for Categories describes a system where you can conveniently perform manipulations with categories, functors, Yoneda embeddings etc. An example of the rules is: $$\frac{\Gamma ,...
10 votes
0 answers
317 views

What's "Swedish" style of doing type theory or proof assistants?

Jon Sterling said Conor McBride's universe polymorphism proposal to be: seems to have worked well in Swedish experiments I wonder, what does "Swedish" mean here? What kind of type theory ...
10 votes
0 answers
175 views

What are the practical differences between intensional and extensional type theories?

It is already proved that MLTT with equality reflection is equivalent to MLTT with an intensional equality, plus UIP and function extensionality. So theoretically the differences between intensional ...
9 votes
0 answers
304 views

Alternatives to universe levels

All of the type theory based proof assistants that I have seen have an infinite hierarchy of type universes to avoid the type of types being a term of itself. Are there alternative systems which could ...
9 votes
0 answers
132 views

Has there been any work on automated translation of tactic proofs to everyday language?

There are times when I've completed a proof with a lot of backwards reasoning, and I've kind of lost the thread of what I've actually done. It would be nice if there was something that could ...
8 votes
0 answers
169 views

Graph algorithms in Coq

We’re looking for a good library for reasoning about graphs in Coq. Some key features with would want to support include: Topological sorting (ideally along with other graph algorithms) Manipulation ...
8 votes
0 answers
287 views

What would a fully classical and fully univalent ITP and library look like?

Consider two developments in dependent type theory: Lean’s mathlib library (as well many other ITP libraries) is unashamedly fully classical. There is no ...

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