Title
Forcing large transitive subtournaments
Abstract
The Erd¿s-Hajnal Conjecture states that for every given H there exists a constant c ( H ) 0 such that every graph G that does not contain H as an induced subgraph contains a clique or a stable set of size at least | V ( G ) | c ( H ) . The conjecture is still open. However some time ago its directed version was proved to be equivalent to the original one. In the directed version graphs are replaced by tournaments, and cliques and stable sets by transitive subtournaments. Both the directed and the undirected versions of the conjecture are known to be true for small graphs (or tournaments), and there are operations (the so-called substitution operations) allowing to build bigger graphs (or tournaments) for which the conjecture holds. In this paper we prove the conjecture for an infinite class of tournaments that is not obtained by such operations. We also show that the conjecture is satisfied by every tournament on at most 5 vertices.
Year
DOI
Venue
2015
10.1016/j.jctb.2014.11.003
J. Comb. Theory, Ser. B
Keywords
Field
DocType
erdos-hajnal conjecture,regularity lemma,tournaments
Discrete mathematics,Combinatorics,Clique,Induced subgraph,Lonely runner conjecture,Independent set,New digraph reconstruction conjecture,Erdős–Hajnal conjecture,Conjecture,Collatz conjecture,Mathematics
Journal
Volume
Issue
ISSN
112
C
0095-8956
Citations 
PageRank 
References 
1
0.41
2
Authors
3
Name
Order
Citations
PageRank
Eli Berger118252.72
Krzysztof Choromanski212423.56
Maria Chudnovsky331061.32