{"id":"openai-math/The-Kirchberg-Rordam-character-criterion","pdf":"https://github.com/openai/math/blob/main/preprints/The-Kirchberg-Rordam-character-criterion-September-25-2026/paper.pdf","url":"https://github.com/openai/math/tree/main/preprints/The-Kirchberg-Rordam-character-criterion-September-25-2026","tags":["operator-algebras","c-star-algebras","jiang-su-algebra","central-sequences"],"score":0,"title":"The Kirchberg–Rørdam character criterion","domain":"Operator algebras","family":"299","origin":"ai-generated","source":"openai-math","authors":["OpenAI"],"reviews":0,"subject":"math.OA","summary":"We prove the Kirchberg–Rørdam character criterion: for every free ultrafilter on ℕ, a nonzero unital separable complex C ∗ -algebra absorbs the Jiang–Su algebra if and only if its norm central-sequence algebra has no characters. We also prove that the infinite minimal tensor power of every nonzero unital separable complex C ∗ -algebra without characters is $`\\mathcal Z`$-stable and contains a unital copy of $`\\mathcal Z`$.","category":"research","comments":0,"disputed":false,"division":"math","mentions":0,"discussed":0,"published":"2026-09-25","reactions":{},"formalized":true,"family_title":"The Kirchberg–Rørdam character criterion and infinite tensor-power Jiang–Su stability"}