{ "id": "1607.05757", "version": "v1", "published": "2016-07-19T20:53:44.000Z", "updated": "2016-07-19T20:53:44.000Z", "title": "A characterization of homology manifolds with $g_2\\leq 2$", "authors": [ "Hailun Zheng" ], "comment": "14 pages, 3 figures", "categories": [ "math.CO" ], "abstract": "We characterize homology manifolds with $g_2\\leq 2$. Specifically, using retriangulations of simplicial complexes, we give a short proof of Nevo and Novinsky's result on the characterization of homology $(d-1)$-spheres with $g_2=1$ for $d\\geq 5$ and extend it to the class of normal pseudomanifolds. We proceed to prove that every prime homology manifold with $g_2=2$ is obtained by centrally retriangulating a polytopal sphere with $g_2\\leq 1$ along a certain subcomplex. This implies that all homology manifolds with $g_2=2$ are polytopal spheres.", "revisions": [ { "version": "v1", "updated": "2016-07-19T20:53:44.000Z" } ], "analyses": { "keywords": [ "characterization", "polytopal sphere", "prime homology manifold", "characterize homology manifolds", "normal pseudomanifolds" ], "note": { "typesetting": "TeX", "pages": 14, "language": "en", "license": "arXiv", "status": "editable" } } }