Show HN: Lean4 proof that SSOT requires definition-time hooks and introspection

Re:Show HN: Lean4 proof that SSOT requires definition-time h... by BalinKing on Thursday January 08, 2026 @12:31PM (#46543794)

> Compare to software verification: when you prove a sorting algorithm correct, the hard work is the loop invariants and the model, not the final QED. Tedious proof steps usually indicate you're fighting your abstractions.

This is a false statement when working with an interactive theorem prover like Lean. Even trivial things require mountains of effort, and even blatantly obvious facts will at least require a case analysis or something. It's a massive usability barrier (and one that AI can hopefully help with).

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Re:Show HN: Lean4 proof that SSOT requires definition-time h... by trissim on Thursday January 08, 2026 @01:14PM (#46544404)

This is addressed in the paper's Preemptive Rebuttals section (Concern 9: "The Proofs Are Trivial").

At 2k lines of lean, the criticism was "these proofs are trivial." At 9k lines of lean with 541 theorems, the criticism is... still "trivial"? At what point does the objection become "I didn't read it"?

The rfl proofs are scaffolding. The substantive proofs (rust_lacks_introspection, Inconsistency.lean, Coherence.lean) are hundreds of lines of actual reasoning. This is in the paper.

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