JCT
2007
13 years 4 months ago
2007
A projective-planar signed graph has no two vertex-disjoint negative circles. We prove that every signed graph with no two vertex-disjoint negative circles and no balancing vertex...
JCT
2007
13 years 4 months ago
2007
We prove a number of relations between the number of cliques of a graph G and the largest eigenvalue (G) of its adjacency matrix. In particular, writing ks (G) for the number of s...
JCT
2007
13 years 4 months ago
2007
JCT
2007
13 years 4 months ago
2007
Abstract. We develop linear representation theory for bicircular matroids, a chief example being a matroid associated with forests of a graph, and bicircular lift matroids, a chief...
JCT
2007
13 years 4 months ago
2007
JCT
2007
13 years 4 months ago
2007
Abstract. We prove that a binary matroid with huge branchwidth contains the cycle matroid of a large grid as a minor. This implies that an infinite antichain of binary matroids ca...
JCT
2007
13 years 4 months ago
2007
JCT
2007
13 years 4 months ago
2007
JCT
2007
13 years 4 months ago
2007
JCT
2007
13 years 4 months ago
2007
Kreweras’ conjecture [1] asserts that any perfect matching of the hypercube Qd, d ≥ 2, can be extended to a Hamilton cycle. We prove this conjecture.