Claude's Fable Cracked an 87 Year Old Math Problem

A 100-year-old conjecture was proved false on a laptop during the World Cup final. Anthropic's Levent Alpoge used Claude Fable 5 to find a three-dimensional counterexample disproving the Jacobian conjecture - we break down what the Jacobian actually is (in Google Maps terms) and why Anthropic is the only lab that can see whether Claude was brilliant or lucky.

Then: 50 companies including Nvidia, Microsoft, Meta, and a16z signed the Open Weights letter telling Washington hands off, OpenAI and Google quietly added their names a day later, and Anthropic is the lone holdout - while reportedly lobbying DC to restrict Chinese weights the whole time. Plus we do the math on the Kimi K3 distillation timeline: Fable 5 was live for 18 days before K3 shipped, so how much Claude is realistically in there?