Compositions of maps and hypermaps. (Compositions des cartes et hypercartes.)
A dominating set in a graph is a connected dominating set of if it induces a connected subgraph of . The connected domatic number of is the maximum number of pairwise disjoint, connected dominating sets in . We establish a sharp lower bound on the number of edges in a connected graph with a given order and given connected domatic number. We also show that a planar graph has connected domatic number at most 4 and give a characterization of planar graphs having connected domatic number 3.
We approach the problem of defining curvature on a graph by attempting to attach a ‘best-fit polytope’ to each vertex, or more precisely what we refer to as a configured star. How this should be done depends upon the global structure of the graph which is reflected in its geometric spectrum. Mean curvature is the most natural curvature that arises in this context and corresponds to local liftings of the graph into a suitable Euclidean space. We discuss some examples.
We study two topological properties of the 5-ary -cube . Given two arbitrary distinct nodes and in , we prove that there exists an - path of every length ranging from to , where . Based on this result, we prove that is 5-edge-pancyclic by showing that every edge in lies on a cycle of every length ranging from to .
We study two topological properties of the 5-ary n-cube . Given two arbitrary distinct nodes x and y in , we prove that there exists an x-y path of every length ranging from 2n to 5n - 1, where n ≥ 2. Based on this result, we prove that is 5-edge-pancyclic by showing that every edge in lies on a cycle of every length ranging from 5 to 5n.
In this paper, we study the existence of cycle double covers for infinite planar graphs. We show that every infinite locally finite bridgeless k-indivisible graph with a 2-basis admits a cycle double cover.