Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
1af697a44b
This PR fixes a regression in `Sym.simp` where rewrite rules whose LHS contains a lambda over a pattern variable (e.g. `∃ x, a = x`) failed to match targets with semantically equivalent structure. `Sym.etaReduceAux` previously refused any eta-reduction whenever the body had loose bound variables, but patterns produced by stripping outer foralls always carry such loose bvars. The eta-reduction therefore skipped patterns while still firing on the target, producing mismatched discrimination tree keys and no match. The fix narrows the check to loose bvars in the range `[0, n)` (those that would actually refer to the peeled binders) and lowers any remaining loose bvars by `n` so that pattern-variable references stay consistent in the reduced expression. The discrimination tree now classifies patterns like `exists_eq_True : (∃ x, a = x) = True` with their full structure rather than falling back to `.other`. Includes a regression test (`sym_simp_1.lean`) and Sebastian Graf's MWE (`sym_eta_mwe.lean`). 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com> |
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