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» On Directed Triangles in Digraphs
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COMBINATORICS
2007
86views more  COMBINATORICS 2007»
13 years 7 months ago
On Directed Triangles in Digraphs
Using a recent result of Chudnovsky, Seymour, and Sullivan, we slightly improve two bounds related to the Caccetta-Haggkvist Conjecture. Namely, we show that if α ≥ 0.35312, th...
Peter Hamburger, Penny E. Haxell, Alexandr V. Kost...
SIAMDM
2008
101views more  SIAMDM 2008»
13 years 7 months ago
Hamilton Cycles in Random Lifts of Directed Graphs
An n-lift of a digraph K, is a digraph with vertex set V (K)
Prasad Chebolu, Alan M. Frieze
JGT
2007
81views more  JGT 2007»
13 years 7 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...
JCT
1998
193views more  JCT 1998»
13 years 7 months ago
Fractional Kernels in Digraphs
The aim of this note is to point out some combinatorial applications of a lemma of Scarf, proved first in the context of game theory. The usefulness of the lemma in combinatorics...
Ron Aharoni, Ron Holzman
EJC
2010
13 years 7 months ago
Counting paths in digraphs
Say a digraph is k-free if it has no directed cycles of length at most k, for k Z+ . Thomass
Paul D. Seymour, Blair Sullivan