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Leanforces
Ring expansion of (a + b)²

Submission cmpgy3b8

by alice·5/22/2026, 2:18:08 PM
GitHub failed
Proof body (as submitted)
theorem answer {R : Type _} [CommRing R] (a b : R) : (a + b)^2 = a^2 + 2*a*b + b^2 := by ring
proof_body_hash: 91fd2504f0005b01e2ab080dae2cb1bb405056c2470cb1c67d38949d1e4d5d1d
Generated Lean file

What the judge actually compiles

-- AUTO-GENERATED by Leanforces. Do not edit by hand.
-- Challenge: C0002
-- Submission: cmpgy3b8x000111l6zxdyfoh2

import Mathlib

namespace Leanforces.Challenges.C0002.Submissions.Submission_cmpgy3b8x000111l6zxdyfoh2

-- ┌── USER SUBMISSION BODY (verbatim) ─────────────────────
theorem answer {R : Type _} [CommRing R] (a b : R) : (a + b)^2 = a^2 + 2*a*b + b^2 := by ring
-- └── USER SUBMISSION BODY END ────────────────────────────

/-- App-appended type check. Refuses to compile unless
    `answer` has type `∀ {R : Type _} [CommRing R] (a b : R), (a + b)^2 = a^2 + 2*a*b + b^2`. -/
def solution_target : ∀ {R : Type _} [CommRing R] (a b : R), (a + b)^2 = a^2 + 2*a*b + b^2 := answer

#print axioms solution_target

end Leanforces.Challenges.C0002.Submissions.Submission_cmpgy3b8x000111l6zxdyfoh2
file_hash (recomputed): dbbdf2058c868455c5c2f9a4f95ff47f7a94ce39b0e13664742d29b5c6cb98ab ✗ DOES NOT match stored hash
GitHub
Branchsubmission/cmpgy3b8x000111l6zxdyfoh2
Commit SHAb4728b66bb5b054ff4935f58953b1e2c400431c2
Workflow runhttps://github.com/ryendo/proofgarden-judge/actions/runs/26290128772
PR #