{ "id": "2410.16002", "version": "v1", "published": "2024-10-21T13:34:38.000Z", "updated": "2024-10-21T13:34:38.000Z", "title": "Profinite almost rigidity in 3-manifolds", "authors": [ "Xiaoyu Xu" ], "comment": "50 pages, comments are welcome!", "categories": [ "math.GT", "math.GR" ], "abstract": "We prove that any compact, orientable 3-manifold with empty or incompressible toral boundary is profinitely almost rigid among all compact, orientable, boundary-incompressible 3-manifolds, i.e. the profinite completion of its fundamental group determines its homeomorphism type up to finitely many possibilities. Moreover, the profinite completion of the fundamental group of a mixed 3-manifold, together with the peripheral structure, uniquely determines the homeomorphism type of its Seifert part (i.e. the maximal graph manifold components in the JSJ-decomposition). On the other hand, without assigning the peripheral structure, the profinite completion of a mixed 3- manifold group may not even determine the fundamental group of its Seifert part. The proof is based on JSJ-decomposition.", "revisions": [ { "version": "v1", "updated": "2024-10-21T13:34:38.000Z" } ], "analyses": { "subjects": [ "57M05", "20E18" ], "keywords": [ "profinite completion", "maximal graph manifold components", "seifert part", "peripheral structure", "homeomorphism type" ], "note": { "typesetting": "TeX", "pages": 50, "language": "en", "license": "arXiv", "status": "editable" } } }