Isabelle
Fewer than 5 people recommend it so far, so there's no written verdict. Here is what commenters said.
4recommend
1warn against
Nov 2, 2025first mention
Oct 6, 2026latest mention
Why people recommend it
“Or, say Isar in Isabelle/ZF [2].”
“re-inventing everything Isabelle has had for decades”
Show 3 more
“the "sledgehammer" tool in there (which uses solvers to see if an existing proof can be made to work to solve your subgoal) is something that impresses me every single time I use it.”
“Isabelle (classical) has a great track record in software verification.”
Caveats and dissent
Often compared with
Threads where it came up
- Broken Proofs and Broken Provers 2 mentions
- Why don't you use dependent types? 2 mentions
- Is mathematics over, or just graduating? 1 mention
- Formalizing Fermat's Last Theorem 1 mention
- Palomar: A registry of Lean verified mathematics 1 mention
- The Fall of the Theorem Economy 1 mention
Data: isabelle.json. Quotes are verbatim; the verdict and theme labels are written by a model from these comments, and every clause links to its sources.
All comments 18
“e.g. https://isabelle.in.tum.de/website-Isabelle2025/dist/Isabelle2025/doc/sledgehammer.pdf”
“Or, say Isar in Isabelle/ZF [2].”
“re-inventing everything Isabelle has had for decades”
“with some UC security reductions done in isabelle”
“The specification is written in Isabelle”
“the only one I've done with any kind of intimate detail is Isabelle.”
“A notable practitioner for Isabelle and Lean is AWS”
“the most mature option is probably Isabelle”
“Isabelle proper is fairly mediocre”
“At least in Isabelle/ML, it seems like in practice there are also untrusted "oracles"”
“Isabelle has a verified proof checker that can check whether a given proof is sound”
“Isabelle has had the "Sledgehammer" tool”
You know what? I agree with you. I have not formalised any of my stuff on abstraction logic [1] for that reason (although that would not be too difficult in Isabelle or Lean), I want to write it down in Practal [2], this becoming possible I see as the first serious milestone for Practal. Eventually, I want Practal to feel more natural than paper, and definitely more natural than LaTeX. That's the goal, and I feel man
“verified it in both Isabelle and Lean4”
“plenty of computer-verified mathematics done in Metamath/set.mm and Isabelle/ZF”
“the "sledgehammer" tool in there (which uses solvers to see if an existing proof can be made to work to solve your subgoal) is something that impresses me every single time I use it.”
“Isabelle (classical) has a great track record in software verification.”
“Isabelle's library of mathematics, the AFP, is organized like a scientific journal with referees”