Claude Fable 5 tops GPT-5.5 in tough math challenge

A fresh benchmark shows Anthropic’s Claude Fable 5 beating OpenAI’s GPT-5.5 by 13 percentage points on the most difficult problems in FrontierMath. The result puts the new model at 88 percent accuracy on the hardest tier, a sharp rise from its predecessor’s sub-10 percent score recorded earlier this year.

Behind the leap in mathematical prowess

FrontierMath is designed to stress-test advanced reasoning, and the latest scores suggest rapid progress in how these systems tackle complex math. Anthropic’s upgrade path—from Opus 4.5’s low single digits to Fable 5’s near-perfect performance—highlights how targeted training and model scaling can yield quick gains in specialized domains.

What this means for the AI race

With OpenAI’s GPT-5.5 still ahead on other benchmarks, the head-to-head result underscores that no single model dominates across all tasks. It also signals that the next wave of AI advances may hinge on domain-specific fine-tuning rather than broad general-purpose scaling.

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Source: The Decoder. AI-assisted editorial synthesis — TechnoExpress.