Let H be a finite family of graphs. A graph G is H-universal if it contains a copy of each H H as a subgraph. Let H(k, n) denote the family of graphs on n vertices with maximum d...
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...
The line index of a graph G is the smallest k such that the kth iterated line graph of G is nonplanar. We show that the line index of a graph is either innite or it is at most 4....
For a positive integer k and a graph G, the k-colour graph of G, Ck(G), is the graph that has the proper k-vertex-colourings of G as its vertex set, and two k-colourings are joine...
Luis Cereceda, Jan van den Heuvel, Matthew Johnson