{ "id": "1301.7356", "version": "v1", "published": "2013-01-30T20:58:17.000Z", "updated": "2013-01-30T20:58:17.000Z", "title": "Fractional Perfect b-Matching Polytopes. I: General Theory", "authors": [ "Roger E. Behrend" ], "comment": "37 pages", "categories": [ "math.CO", "cs.DM" ], "abstract": "The fractional perfect b-matching polytope of an undirected graph G is the polytope of all assignments of nonnegative real numbers to the edges of G such that the sum of the numbers over all edges incident to any vertex v is a prescribed nonnegative number b_v. General theorems which provide conditions for nonemptiness, give a formula for the dimension, and characterize the vertices, edges and face lattices of such polytopes are obtained. Many of these results are expressed in terms of certain spanning subgraphs of G which are associated with subsets or elements of the polytope. For example, it is shown that an element u of the fractional perfect b-matching polytope of G is a vertex of the polytope if and only if each component of the graph of u either is acyclic or else contains exactly one cycle with that cycle having odd length, where the graph of u is defined to be the spanning subgraph of G whose edges are those at which u is positive.", "revisions": [ { "version": "v1", "updated": "2013-01-30T20:58:17.000Z" } ], "analyses": { "subjects": [ "52B05", "05C50", "05C70", "52B11", "90C27", "90C35" ], "keywords": [ "fractional perfect b-matching polytope", "general theory", "spanning subgraph", "nonnegative real numbers", "face lattices" ], "note": { "typesetting": "TeX", "pages": 37, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2013arXiv1301.7356B" } } }