An Artin group with no geometric CAT(0) action
We construct an Artin group on 116 generators that admits no proper, cocompact isometric action on a nonempty proper CAT(0) space. This refutes the CAT(0) conjecture for Artin groups.
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100+ reactions to 100+ solutionsProofs and PromptsOct 8, 2026
116 generators, but after feeding it to Astra, in 10 minutes I got a new example with 12 generators. Clearly, they were in a rush to post the big drop, prioritizing quantity over quality…Why? This does not solve the misalignment between labs and academics at all; indeed, the question remains: are…