Epoch AI releases FrontierMath v2, correcting 42% of problems; Fable 5 leads
Epoch AI·medium signal
On 2026-06-12 Epoch AI shipped FrontierMath v2, which fixed errors in 42% of problems; the full set is now 338 problems (295 in Tiers 1–3, 43 in the Tier-4 expansion). Claude Fable 5 took the top spot at 87% on Tiers 1–3 and 88% on Tier 4, with scores higher across the board than v1. Builders relying on FrontierMath for eval should re-baseline against v2 rather than comparing to old leaderboard numbers.