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JGT
2007
99views more  JGT 2007»
14 years 11 months ago
The upper bound of the number of cycles in a 2-factor of a line graph
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...
Jun Fujisawa, Liming Xiong, Kiyoshi Yoshimoto, She...
JGT
2007
81views more  JGT 2007»
14 years 11 months ago
Maximum directed cuts in acyclic digraphs
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...
Noga Alon, Béla Bollobás, Andr&aacut...
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JGT
2007
54views more  JGT 2007»
14 years 11 months ago
Overlap in consistent cycles
: 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...
Stefko Miklavic, Primoz Potocnik, Steve Wilson
JGT
2007
85views more  JGT 2007»
14 years 11 months ago
Coloring quasi-line graphs
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 ...
Maria Chudnovsky, Alexandra Ovetsky
JGT
2007
69views more  JGT 2007»
14 years 11 months ago
The size of minimum 3-trees
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 ...
Jorge L. Arocha, Joaquín Tey