Unanswered Questions

35 questions with no upvoted or accepted answers
18 votes
0 answers
162 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 ...
18 votes
0 answers
188 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
113 views

Programming language metatheory in Lean 4?

I'm looking for developments of programming language metatheory done in Lean 4. We have a calculus with a lot of mutually recursive judgements and we want to formalise its denotational semantics. ...
15 votes
0 answers
109 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 ...
12 votes
0 answers
147 views

How do Coq's bidirectionality hints (`&`) affect type checking?

I have used Coq's bidirectionality hints (placement of & in a call to Arguments) to some effect, mostly by trial and error. ...
12 votes
0 answers
255 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 ...
11 votes
0 answers
153 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 ,...
11 votes
0 answers
294 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 ...
11 votes
0 answers
129 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 ...
11 votes
0 answers
76 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 ...
11 votes
0 answers
172 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
149 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-...
9 votes
0 answers
114 views

Learning materials for doing analysis (calculus) in a mechanized way

Can we collect (or maybe even write) tutorials and guides on doing analysis in various Proof Assistants? Community wiki style? I was reading Lawrence Paulson's blog (highly recommend!) the other week ...
7 votes
0 answers
62 views

What is focusing and how do I use it?

I have heard the term "focusing" with respect to the sequent calculus (System LK) and related calculi like the $\bar{\lambda} \mu \tilde{\mu}$-calculus. What is focusing and how do I use it? ...
7 votes
0 answers
95 views

Tutorial implementations of extensional type theories

There are cool projects out there that covers the basic principles of implementing dependent type theories as very spartan proof assistants. These projects helped a lot when I learned about (...

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