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JGT
2007
13 years 9 months ago
2007
Let G be a simple graph with order n and minimum degree at least two. In this paper, we prove that if every odd branch-bond in G has an edge-branch, then its line graph has a 2-fa...
JGT
2007
13 years 9 months ago
2007
It is easily shown that every digraph with m edges has a directed cut of size at least m/4, and that 1/4 cannot be replaced by any larger constant. We investigate the size of a la...
JGT
2007
13 years 9 months ago
2007
: A (directed) cycle C in a graph is called consistent provided there exists an automorphism of , acting as a 1-step rotation of C. A beautiful but not well-known result of J.H. Co...
JGT
2007
13 years 9 months ago
2007
A graph G is a quasi-line graph if for every vertex v, the set of neighbors of v can be expressed as the union of two cliques. The class of quasi-line graphs is a proper superset ...
JGT
2007
13 years 9 months ago
2007
A 3-uniform hypergraph is called a minimum 3-tree, if for any 3-coloring of its vertex set there is a heterochromatic triple and the hypergraph has the minimum possible number of ...