{ "id": "2111.10568", "version": "v2", "published": "2021-11-20T11:53:37.000Z", "updated": "2022-04-18T18:09:16.000Z", "title": "On the structure of the top homology group of the Johnson kernel", "authors": [ "Igor A. Spiridonov" ], "comment": "22 pages", "categories": [ "math.GT", "math.GR" ], "abstract": "The Johnson kernel is the subgroup $\\mathcal{K}_g$ of the mapping class group ${\\rm Mod}(\\Sigma_{g})$ of a genus $g$ oriented closed surface $\\Sigma_{g}$ generated by all Dehn twists about separating curves. In this paper we study the structure of the top homology group ${\\rm H}_{2g-3}(\\mathcal{K}_g, \\mathbb{Z})$. For any collection of $2g-3$ disjoint separating curves on $\\Sigma_{g}$ one can construct the corresponding abelian cycle in the group ${\\rm H}_{2g-3}(\\mathcal{K}_g, \\mathbb{Z})$; such abelian cycles will be called simplest. In this paper we describe the structure of $\\mathbb{Z}[{\\rm Mod}(\\Sigma_{g})/ \\mathcal{K}_g]$-module on the subgroup of ${\\rm H}_{2g-3}(\\mathcal{K}_g, \\mathbb{Z})$ generated by all simplest abelian cycles and find all relations between them.", "revisions": [ { "version": "v2", "updated": "2022-04-18T18:09:16.000Z" } ], "analyses": { "subjects": [ "20F34", "20F36", "57M07", "20J05" ], "keywords": [ "johnson kernel", "homology group", "simplest abelian cycles", "dehn twists", "disjoint separating curves" ], "note": { "typesetting": "TeX", "pages": 22, "language": "en", "license": "arXiv", "status": "editable" } } }