OpenAI exits Caltech Mathathon after mathematicians object

Current and former Caltech mathematicians, writing as a coalition on Proofs and Prompts, published an open letter about the Mathathon on 10 September 2026. They ask organizers to suspend the student-led Caltech Mathathon that is set to start on 30 October 2026, where participants prompt large language models on open research problems.

This is a community open letter from eligible Caltech affiliates and research mathematicians. It is not an OpenAI press release, and it is not a Caltech cancellation of the event.

The letter says Anthropic and OpenAI together were to supply $2 million in AI credits. At publication it listed 771 signatories, and the form remains open for more eligible names (Caltech community members, or research mathematicians at PhD level or higher). The authors warn of "slop mathematics," unpaid verification labor after rushed AI-generated claims, and they say AI companies are engaging in "research misconduct."

Business Insider (Truman Dickerson, 10 September 2026) reported that OpenAI research lead Dan Roberts said on X that OpenAI is no longer sponsoring. Roberts also said the company wants to engage the math community on how to integrate the technology and communicate its impacts.

The letter page links a response from the organizers, and their framing of the event continues. Anthropic's sponsorship after OpenAI's exit is not settled in the letter. Business Insider said Anthropic did not immediately comment, and it was unclear how the $2 million credit pool splits now. This Caltech letter is separate from a Fields Medalists letter that circulated the same week.

OpenAI capacity and product notes sit next to the ChatGPT Pro pause amid Astra demand and ChatGPT Finance at Morgan Stanley. Other model tape includes DeepSeek V4.1 Flash and NASA and IBM's lunar foundation model.

If you planned to attend or staff the Mathathon, treat 30 October as still on unless the organizers later cancel, and treat Anthropic as still named in the original credit plan until they say otherwise. Eligible mathematicians who want their name on the record can still add it on the letter page.