We extend the colourful complete bipartite subgraph theorems of [G. Simonyi, G. Tardos, Local chromatic number, Ky Fan's theorem, and circular colorings, Combinatorica 26 (2006), 587--626] and [G. Simonyi, G. Tardos, Colorful subgraphs of Kneser-like graphs, European J. Combin. 28 (2007), 2188--2200] to more general topological settings. We give examples showing that the hypotheses are indeed more general. We use our results to show that the topological bounds on chromatic numbers of digraphs with tree duality are at most one better than the clique number. We investigate combinatorial and complexity-theoretic aspects of relevant order-theoretic maps.
@article{10_37236_2302,
author = {G\'abor Simonyi and Claude Tardif and Ambrus Zsb\'an},
title = {Colourful theorems and indices of homomorphism complexes},
journal = {The electronic journal of combinatorics},
year = {2013},
volume = {20},
number = {1},
doi = {10.37236/2302},
zbl = {1266.05041},
url = {http://geodesic.mathdoc.fr/articles/10.37236/2302/}
}
TY - JOUR
AU - Gábor Simonyi
AU - Claude Tardif
AU - Ambrus Zsbán
TI - Colourful theorems and indices of homomorphism complexes
JO - The electronic journal of combinatorics
PY - 2013
VL - 20
IS - 1
UR - http://geodesic.mathdoc.fr/articles/10.37236/2302/
DO - 10.37236/2302
ID - 10_37236_2302
ER -
%0 Journal Article
%A Gábor Simonyi
%A Claude Tardif
%A Ambrus Zsbán
%T Colourful theorems and indices of homomorphism complexes
%J The electronic journal of combinatorics
%D 2013
%V 20
%N 1
%U http://geodesic.mathdoc.fr/articles/10.37236/2302/
%R 10.37236/2302
%F 10_37236_2302
Gábor Simonyi; Claude Tardif; Ambrus Zsbán. Colourful theorems and indices of homomorphism complexes. The electronic journal of combinatorics, Tome 20 (2013) no. 1. doi: 10.37236/2302