Báo cáo toán học: "Uniquely Hamiltonian Characterizations of Distance-Hereditary and Parity Graphs" ppsx

... 417–420. the electronic journal of combinatorics 15 (2008), #N36 5 Uniquely Hamiltonian Characterizations of Distance-Hereditary and Parity Graphs Terry A. McKee Department of Mathematics & Statistics Wright ... H is an induced subgraph of G and so has an even number of hamiltonian cycles. Suppose v  is the twin of some v ∈ V (G). If v  ∈ V (H), then H has an...

Ngày tải lên: 07/08/2014, 15:22

... 97e:05058. Connects a problem on common covectors of two subspaces of R m ,andmore generally of a pair of oriented matroids, to the problem of sign-solvability of a matrix and the even-cycle problem for signed ... Cornu´ejols and Guenin (20xxa), Guenin (1998a), and Novick and Seb¨o (1995a) (qq.v.). (S(M), SG: M, G, I(Gen), O: Exp, Ref, Exr) G´erard Cornu´ejols and Bertra...

Ngày tải lên: 07/08/2014, 05:23

... a k and b k the (constant) values of c, a and b, respectively, over every vertex of C k , and we refer to them as the pseudo-intersection numbers of C. Not e that when Γ is a regular graph and ... definition of Terwilliger to a set of vertices in any graph, and prove its equivalence with t he combinatorial approach. This allows us to give new proo fs of known results, an...

Ngày tải lên: 08/08/2014, 12:22

Ngày tải lên: 05/08/2014, 15:20

... other random variables: the number of descendants D n and the number of ascendants A n of a randomly chosen internal node in a random search tree of size n. This corresponds to averaging D n,j and ... number of comparisons to sort a random permutation of size n,when the recursion stops in subfiles of size ≤ b and the pivots are selected as the median of samples of three...

Ngày tải lên: 07/08/2014, 06:22

... k<n,asubtableau of shape 2 × k of a vertical tableau ∆ of shape 2 × n is a subset of k columns of ∆. A partial tableau is a collection of k columns which is a subtableau of at least one vertical ... assumption that the combination of rows of K 2 × n is nontrivial. For a given horizontal tableau Γ, let a Γ and b Γ be the numbers of elements of {1, ,n} in the rows of...

Ngày tải lên: 07/08/2014, 08:22

... A of the diagram is bounded by s. Similarly, the number of points in each of regions B, C, D,andE must also be bounded by s. The set of common neighbors of 1 and t must be some subset of all of ... from the proof of Theorem 1.3, as if the structure of a permutation is ‘close’ to that of π s,m n then the configuration of the first type in Figure 2 will not occur for most...

Ngày tải lên: 07/08/2014, 13:21

... permutation of rows and columns A is a block diagonal matrix in which each block is a square all-1 matrix. Proof of Theorem 1.1: The square of the number of perfect matchings of G counts ordered pairs of ... came from M 1 and which from M 2 . The permanent of the adjacency matrix A of G also counts the number of spanning 2-regular subgraphs H  of G, where now we allow...

Ngày tải lên: 07/08/2014, 15:22

... consisting of any number of 2  s and 1  s, and its subset of bipartite graphs, we characterize the optimal graphs who maximize and minimize the number of m-matchings. We find the expected value of the ... (2.12-2.15) hold if and only if G is either a union of copies of C 4 , or a union of copies of C 4 and a copy of C i for i = 5, 6, 7, respectively. Equalities...

Ngày tải lên: 07/08/2014, 21:20

... the prod- uct topology of the space of functions on Γ and has the property of uniqueness of the barycentric decomposition of each v ∈ V over the set of extreme elements of V (see, e. g., [8, Proposition ... distribution on Gr (V ∞ ) defines a random subspace of V ∞ . We loo k at random subspaces of V ∞ whose distribution is invariant under the action of G ∞ . Observe that...

Ngày tải lên: 07/08/2014, 21:21