Hi. I’m Gareth McCaughan. I’ve been a consistent reader and occasional commenter since the Overcoming Bias days. My LW username is “gjm” (not “Gjm” despite the wiki software’s preference for that capitalization). Elsewehere I generally go by one of “g”, “gjm”, or “gjm11”. The URL listed here is for my website and blog, neither of which has been substantially updated for several years. I live near Cambridge (UK) and work for Hewlett-Packard (who acquired the company that acquired what remained of the small company I used to work for, after they were acquired by someone else). My business cards say “mathematician” but in practice my work is a mixture of simulation, data analysis, algorithm design, software development, problem-solving, and whatever random engineering no one else is doing. I am married and have a daughter born in mid-2006. The best way to contact me is by email: firstname dot lastname at pobox dot com. I am happy to be emailed out of the blue by interesting people. If you are an LW regular you are probably an interesting person in the relevant sense even if you think you aren’t.
If you’re wondering why some of my very old posts and comments are at surprisingly negative scores, it’s because for some time I was the favourite target of old-LW’s resident neoreactionary troll, sockpuppeteer and mass-downvoter.
The answers, at least for OpenAI and Google, have been posted.
OpenAI: https://github.com/aw31/openai-imo-2025-proofs/
Google: https://storage.googleapis.com/deepmind-media/gemini/IMO_2025.pdf
The OpenAI solutions are written in a weird style (I have seen some people say “RLHFed to death” and some people say “looks like internal chain-of-thought language” and some people say “it’s learned to be brief to get maximum use out of its context window”) but still basically natural mathematical language.
The Google solutions—I don’t know whether this is exactly what the model spat out or whether it’s been through any prettifying postprocessing, but would guess the former—are neatly formatted and written in nice polished English with LaTeX-formatted mathematics.
The ones I’ve looked at (which is not all of them) seem to be genuinely complete solutions, aside from the weird language of the OpenAI ones.
So far as I know, the prompts have not been posted.
(Some other people used ordinary Gemini 2.5 Pro to solve some of the problems—I forget whether they managed all of them other than #6 or not—with a bit more human assistance; I don’t think they posted their exact prompts but they did mention things like saying “Let’s proceed by induction” after the statement of Q1 and “Let’s do this with analytic geometry” after the statement of Q2. For the solutions above, I think OpenAI and Google both claim not to have given any sort of hints,)