{ "id": "1307.1356", "version": "v1", "published": "2013-07-04T14:43:12.000Z", "updated": "2013-07-04T14:43:12.000Z", "title": "On equivariant Euler-Poincaré characteristic in sheaf cohomology", "authors": [ "Steffen Kionke", "Jürgen Rohlfs" ], "comment": "7 pages, no figures", "categories": [ "math.AT" ], "abstract": "Let X be a topological Hausdorff space together with a continuous action of a finite group G. Let R be the ring of integers of a number field F. Let E be a G-sheaf of flat R-modules over X and let $\\Phi$ be a G-stable paracompactifying family of supports on X. We show that under some natural cohomological finiteness conditions the Lefschetz number of the action of g in G on the cohomology $H_\\Phi(X,E) \\otimes_{R} F$ equals the Lefschetz number of the g-action on $H_\\Phi(X^g, E_{|X^g}) \\otimes_{R} F$, where $X^g$ is the set of fixed points of g in X. More generally, the class $\\sum_j (-1)^j [H^j_\\Phi (X,E) \\otimes_R F]$ in the character group equals a sum of representations induced from irreducible F-rational representations $V_\\lambda$ of $H$ where $H$ runs in the set of G-conjugacy classes of subgroups of G. The integral coefficients $m_\\lambda$ in this sum are explicitly determined.", "revisions": [ { "version": "v1", "updated": "2013-07-04T14:43:12.000Z" } ], "analyses": { "subjects": [ "55N30", "54H15" ], "keywords": [ "sheaf cohomology", "characteristic", "equivariant", "lefschetz number", "natural cohomological finiteness conditions" ], "note": { "typesetting": "TeX", "pages": 7, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2013arXiv1307.1356K" } } }