←Back to NewsAI News/ReasoningnewsReasoningBenchmarksVals AI Finds Claude Opus 5.5 Beats GPT-6 Astra on Math ProofsVals AI ran GPT-6 Astra, Claude Opus 5, and Opus 5.5 across five reasoning levels on Lean 4 proof tasks and found diminishing returns kick in fast.SourceVals AIPublishedSep 25, 2026, 12:41 AMAuthorAlphaSignal NewsroomRead1 min readVals AI ran GPT-6 Astra, Claude Opus 5, and Opus 5.5 across five reasoning levels on Lean 4 proof tasks and found diminishing returns kick in fast.Reporting is indexed from AlphaSignal. Rights remain with the original publisher and cited sources.Read original report ↗Next readsEpoch AI · newsGPT-6 Astra Cracks a Decade-Old Voting Theory Problem Nobody Could SolveVals AI · newsVals AI's MysteryMechanism Benchmark Tests If AI Can Rediscover 222 Scientific LawsEpoch AI · newsOpenAI's GPT-6 Astra Cracks Epoch's Hardest Math Benchmark in 14 Months
