Báo cáo toán học: "Nowhere-zero k-flows of supergraphs" docx

Ngày tải lên: 05/08/2014, 15:20

... multiplicities of eigenvalues 0 and −1 of G. Observe that two vertices of G belong to the same cluster (or to the set of isolated vertices) exactly if the corresponding leaves of T have a common ... fixed vertex of M, • −1 in turn to exactly one other vertex of M, • 0 to all other vertices of G. Then the constructed vectors constitute a simply structured basis of Eig(−1; G)....

Ngày tải lên: 07/08/2014, 21:21

... v i v  i v  j v j and a segment of C form a cycle in G of the electronic journal of combinatorics 8 (2001), #R20 3 Nowhere-zero k-flows of supergraphs Bojan Mohar ∗ and Riste ˇ Skrekovski ∗ Department of Mathematics, University ... in Q is of length ≥ 6, we can color at least 6 7 of the edges of Q using colors 1 and 2. Color every edge of the 1-factor E(G) − E(Q) by color...

Ngày tải lên: 07/08/2014, 06:22

Ngày tải lên: 05/08/2014, 10:20

... of all vertices of T and even splitting of all vertices of V − T. If the edge f  of G s is the image of the edge f of G then we let x s f  = x f . We let x s e =1for the remaining edges e of ... functions of T -joins and k-cuts of graphs. A graph is a pair G =(V,E)whereV is a set and E is a set of unordered pairs of elements of V . The elements of V are called ve...

Ngày tải lên: 07/08/2014, 06:20

... chain of length k of the filling is a selection of rows r 1 < · · · < r k and columns c 1 < · · · < c k such that the cells (r i , c i ) are nonempty. A ne chain of length k of the ... adjacency matrix of a graph on [n] in the diagram ∆ n = (n−1, n−2, . . . , 2, 1) (this encoding was used by Krattenthaler in [2] to give alternative proofs of some of the results of...

Ngày tải lên: 07/08/2014, 13:21

... noncombinatorial proof of (2) by a modified Riordan array theorem derived from theorems in Sprugnoli et al. [5]. Also we refine the formula for C β,γ (n) with aids of a Gould classes of inverse relation ... supported by the 973 Project, the PCSIRT Project of the Ministry of Education, the Ministry of Science and Technology and the National Science Foundation of China. References [...

Ngày tải lên: 07/08/2014, 15:23

... concept of list colorings. This generalization is based on a different point of view. Instead of assigning color lists L v of size ℓ v to the vertices v of a (hyper)graph, we assign sets of vertices ... introduction of paintability of graphs in [Scha2] and the purely combinatorial proof of the Alon-Tarsi List Coloring Theorem in [Scha3]. We also point out that, beside our pai...

Ngày tải lên: 08/08/2014, 12:23

... of either α or β produces a k of size at least m, the later removal of fragments of size less than m cannot affect the k found by the algorithm. Due to validity preservation, removal of any of ... node n 1 of γ L , we let π(n 1 ) de- note the stripe of adjacent rows of π addressed by substring σ(n 1 ) of σ(n L ). If n 1 dominates n 2 in γ L , we let π(n 1 , n 2 ) denote th...

Ngày tải lên: 17/03/2014, 02:20

... conductivity values of BLTM were lower than those of undoped BLT ceramic regardless of measurement frequency. This seemed to be the effect of the donor dopant on the electrical conductivity of a p-type ... properties of (1 – x)PMN–xPZT ferroelectric ceramics. Phys Solid State 2000, 42:936-943. 21. Baudry L: Theoretical investigation of the influence of space charges on f...

Ngày tải lên: 20/06/2014, 20:20