An extremal result for graphs with an application to their colourings.
We derive an upper bound on the number of vertices in graphs of diameter 3 and given degree arising from Abelian lifts of dipoles with loops and multiple edges.
The basis number of a graph is defined by Schmeichel to be the least integer such that has an -fold basis for its cycle space. MacLane showed that a graph is planar if and only if its basis number is . Schmeichel proved that the basis number of the complete graph is at most . We generalize the result of Schmeichel by showing that the basis number of the -th power of is at most .
A subset of the vertex set of a graph is called dominating in , if for each there exists adjacent to . An antidomatic partition of is a partition of , none of whose classes is a dominating set in . The minimum number of classes of an antidomatic partition of is the number of . Its properties are studied.
Associative products are defined using a scheme of Imrich & Izbicki [18]. These include the Cartesian, categorical, strong and lexicographic products, as well as others. We examine which product ⊗ and parameter p pairs are multiplicative, that is, p(G⊗H) ≥ p(G)p(H) for all graphs G and H or p(G⊗H) ≤ p(G)p(H) for all graphs G and H. The parameters are related to independence, domination and irredundance. This includes Vizing's conjecture directly, and indirectly the Shannon capacity of a graph...
We compare the asymptotic growth of the order of the digraphs arising from a construction of Comellas and Fiol when applied to Faber-Moore digraphs versus plainly the Faber-Moore digraphs for the corresponding degree and diameter.