Lean Theorem Proving

Tsinghua University and Moonshot AI released TCSExam, a 100-task expert-reviewed benchmark spanning Lean theorem proving, solver engineering, record-setting constructions, and 30 open conjectures, with every submission verified by the Lean kernel or a task checker. GPT-6 Astra fully proved 70.0% of theorems without supplied lemmas, versus 38.3% for Kimi K3.1 Pro and at most 11.7% for six other agents, yet the same model solved none of the 30 open TCS conjectures; the few accepted conjecture submissions merely adapted counterexamples and proofs OpenAI had already published.