GPT-5.5 Used to Flag Fatal Errors in ~1/3 of FrontierMath Tiers 1-4 Problems

Epoch AI·high signal

Epoch AI disclosed that an AI-assisted review using GPT-5.5 found fatal errors in approximately one-third of FrontierMath Tiers 1-4 problems — the benchmark meant to evaluate frontier AI math capabilities. OpenAI's Noam Brown confirmed the initial review was AI-assisted. This is significant because FrontierMath was considered one of the hardest AI benchmarks; systematic errors in the problems themselves undermine reported scores across all models. Benchmark version bumped to 1.1.4 after corrections.