Checked fact 446210 Nov 2026Research

The post says the first formalization, performed by an unreleased research version of Claude, took 11 days and relied on a purpose-built harness along with guidance from a human researcher.

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The exact words it rests on

took 11 days ... relied on a purpose-built harness along with guidance from a human researcher.

What the source said when we opened it, on 10 Nov 2026.

The source

Claude Fable 5.2 and Claude Mythos 5.2
Anthropic · 2026-11-09

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Checked by the notis newsroom on 10 Nov 2026, against the source above.

In the story

Anthropic says 1,000 Fable 5.2 agents formalized Fermat's Last Theorem in Lean in 30 hours; the post names no checker. 10 Nov 2026

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The company says: “The post says the first formalization, performed by an unreleased research version of Claude, took 11 days and relied on a purpose-built harness along with guidance from a human researcher.” ai notis, checked 10 Nov 2026. Source: Claude Fable 5.2 and Claude Mythos 5.2 (Anthropic). https://ainotis.com/c/4462

As a reference (APA style)

ai notis. (2026, November 10). The company says: The post says the first formalization, performed by an unreleased research version of Claude, took 11 days and relied on a purpose-built harness along with guidance from a human researcher [Checked claim 4462]. ai notis. https://ainotis.com/c/4462

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