DMTCS Proceedings, 2005 European Conference on Combinatorics, Graph Theory and Applications (EuroComb '05)

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DMTCS Conference vol AE (2005), pp. 117-122

DMTCS

2005 European Conference on Combinatorics, Graph Theory and Applications (EuroComb '05)

Stefan Felsner (ed.)

DMTCS Conference Volume AE (2005), pp. 117-122


author: Richard Anstee, Balin Fleming, Zoltán Füredi and Attila Sali
title: Color critical hypergraphs and forbidden configurations
keywords: forbidden configuration, color critical hypergraph, linear algebra method
abstract: The present paper connects sharpenings of Sauer's bound on forbidden configurations with color critical hypergraphs. We define a matrix to be simple if it is a (0,1)-matrix with no repeated columns. Let
F
be a
k× l
(0,1)-matrix (the forbidden configuration). Assume
A
is an
m× n
simple matrix which has no submatrix which is a row and column permutation of
F
. We define
forb
(m,F)
as the best possible upper bound on
n
, for such a matrix
A
, which depends on
m
and
F
. It is known that
forb
(m,F)=O(m
k
)
for any
F
, and Sauer's bond states that
forb
(m,F)=O(m
k-1
)
fore simple
F
. We give sufficient condition for non-simple
F
to have the same bound using linear algebra methods to prove a generalization of a result of Lovász on color critical hypergraphs.
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reference: Richard Anstee and Balin Fleming and Zoltán Füredi and Attila Sali (2005), Color critical hypergraphs and forbidden configurations, in 2005 European Conference on Combinatorics, Graph Theory and Applications (EuroComb '05), Stefan Felsner (ed.), Discrete Mathematics and Theoretical Computer Science Proceedings AE, pp. 117-122
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