Báo cáo toán học: "Maximum matchings in regular graphs of high girth" ppt

... electronic journal of combinatorics 14 (2007), #N1 4 Maximum matchings in regular graphs of high girth Abraham D. Flaxman Microsoft Research Redmond, Washington, USA abie@microsoft.com Shlomo Hoory IBM ... The set of incidence vectors of the matchings of G have a convex hull which is equal to the polytope containing all x ∈ R E which satisfy the following the electronic...

Ngày tải lên: 07/08/2014, 13:21

... Perfect matchings in  -regular graphs Noga Alon ∗ School of Mathematics, Institute for Advanced Study, Princeton, NJ 08540 and Department of Mathematics, Raymond and Beverly Sackler Faculty of Exact ... M(G) ≤ (d +2) n n!. Thus, the number of perfect matchings in any super (d, ) -regular graph on 2n vertices is close to the expected number of such matchings in a r...

Ngày tải lên: 07/08/2014, 06:22

... the maximal size of a matching in H. A cover of a hypergraph H is a subset of V (H) meeting all hyperedges of H. The covering number, τ(H), of H is the minimal size of a cover of H. Obviously, ... (G), then G has a heterochromatic matching of cardinality  2k 3  . In this paper, we study heterochromatic matchings in general graphs and obtain the following result. Th...

Ngày tải lên: 07/08/2014, 21:21

... t, no two of which sharing an edge, h as an s-colored t-matching contained in its union. In the case r = 2 the conjecture is that a set of t+1 disjoint t -matchings has a t-rainbow matching. This ... consist of s − 1 copies of each matching M(p), p ∈ {0, 1} [r−1] . Let M be a matching of size t contained in the union of the matchings M(p). Clearly, M is perfect, namely it...

Ngày tải lên: 08/08/2014, 01:20

... 2-fa ctor of H using many of the specified edges of H so that when transforming this 2-factor of H to that of G, each of those edges of H has many ways to make 2-factors of G. 2 Structure of 2-edge-connected ... permanents of certain (0, 1)-matrices. Nederl. Aka d. Wetensch. Ind ag. Math., 41(1):83– 86, 1979. the electronic journal of combinatorics 18 (2011), #P62 6 Perfe...

Ngày tải lên: 08/08/2014, 14:22

... graph. A rainbow matching of G is a matching in which no two edges have the same color. Let δ denote the minimum degree of G. We show that if |V (G)| ≥ 8δ 5 , then G has a rainbow matchin g of size ... then G has a rainbow matchin g of size at least ⌊ 2δ 3 ⌋. Keywords: rainbow matchings, properly colored graphs, triangle-free graphs 1 Introduction and notation We use [3] for ter...

Ngày tải lên: 08/08/2014, 14:23

Ngày tải lên: 05/08/2014, 09:46

Ngày tải lên: 05/08/2014, 15:20

... See http://mathworld.wolfram.com/BernsteinPolynomial.html the electronic journal of combinatorics 10 (2003), #R15 17 A Discontinuity in the Distribution of Fixed Point Sums Edward A. Bender Department of Mathematics University of ... an interesting steep drop from r = n to r = n + 1, and this paper arose in providing a quantification of the observed plunge. We think that this pro...

Ngày tải lên: 07/08/2014, 07:21

... vertex in Q k (x)containsk+1 vertices in Q k (x). A ball centered on some vertex in a Q k (y) such that d(y, x) = 1 contains exactly one vertex in Q k (x). We consider γ theminimumnumberofverticesofthecodewecanfindinaQ k (x). Let ... tilings of the grid Z n by balls of radius 1. Perfect codes have also been studied on other alphabets or mixed one (see [2]). In [1], Biggs introduc...

Ngày tải lên: 07/08/2014, 13:21