The acyclic polynomial of a graph.
We consider the multiple ellipses detection problem on the basis of a data points set coming from a number of ellipses in the plane not known in advance, whereby an ellipse is viewed as a Mahalanobis circle with center , radius , and some positive definite matrix . A very efficient method for solving this problem is proposed. The method uses a modification of the -means algorithm for Mahalanobis-circle centers. The initial approximation consists of the set of circles whose centers are determined...
We extend two results of Ruzsa and Vu on the additive complements of primes.
A transit function on a set is a function satisfying the axioms , and , for all . The all-paths transit function of a connected graph is characterized by transit axioms.
We prove that the automorphism group of the random lattice is not amenable, and we identify the universal minimal flow for the automorphism group of the random distributive lattice.
A balanced colouring of a graph G is a colouring of some of the vertices of G with two colours, say red and blue, such that there is the same number of vertices in each colour. The balanced decomposition number f(G) of G is the minimum integer s with the following property: For any balanced colouring of G, there is a partition V (G) = V1 ∪˙ · · · ∪˙ Vr such that, for every i, Vi induces a connected subgraph of order at most s, and contains the same number of red and blue vertices. The function f(G)...
The basis number of a graph was defined by Schmeichel to be the least integer such that has an -fold basis for its cycle space. He proved that for , the basis number of the complete bipartite graph is equal to 4 except for , and with . We determine the basis number of some particular non-planar graphs such as and , , and -cages for , and the Robertson graph.