{ "id": "2404.11371", "version": "v1", "published": "2024-04-17T13:31:26.000Z", "updated": "2024-04-17T13:31:26.000Z", "title": "The boundary of bordified Outer space", "authors": [ "Karen Vogtmann" ], "comment": "10 pages, 1 figure", "categories": [ "math.GR", "math.GT" ], "abstract": "We study the boundary of the \"Jewel space\" $\\mathcal J_n$ constructed in arXiv:1709.01296. This is an equivariant deformation retract of Outer space $CV_n$ on which $Out(F_n)$ acts properly and cocompactly, and is homeomorphic to the Bestvina-Feighn bordification of $CV_n$. In the current paper we analyze the structure of the boundary of $\\mathcal J_n$. We then use the desctiption of the simplicial closure $CV_n^*$ as the sphere complex of a connected sum of $n$ copies of $S^1\\times S^2$ to prove that this boundary is homotopy equivalent to the subcomplex of $CV_n^*$ spanned by vertices at infinity.", "revisions": [ { "version": "v1", "updated": "2024-04-17T13:31:26.000Z" } ], "analyses": { "subjects": [ "20E36", "20F65", "57M07" ], "keywords": [ "bordified outer space", "equivariant deformation retract", "bestvina-feighn bordification", "jewel space", "current paper" ], "note": { "typesetting": "TeX", "pages": 10, "language": "en", "license": "arXiv", "status": "editable" } } }