{ "id": "2406.08017", "version": "v1", "published": "2024-06-12T09:17:59.000Z", "updated": "2024-06-12T09:17:59.000Z", "title": "The defect of weak approximation for a reductive group over a global field", "authors": [ "Mikhail Borovoi" ], "comment": "12 pages; comments are welcome!", "categories": [ "math.RT", "math.AG", "math.GR", "math.NT" ], "abstract": "Using ideas of Sansuc and of Colliot-Th\\'el\\`ene and a result of Tate, we compute the defect of weak approximation for a reductive group G over a global field K in terms of the algebraic fundamental group of G.", "revisions": [ { "version": "v1", "updated": "2024-06-12T09:17:59.000Z" } ], "analyses": { "subjects": [ "11E72", "20G10", "20G20", "20G25", "20G30" ], "keywords": [ "weak approximation", "global field", "reductive group", "algebraic fundamental group" ], "note": { "typesetting": "TeX", "pages": 12, "language": "en", "license": "arXiv", "status": "editable" } } }