Title
The structure of bi-arc trees
Abstract
Bi-arc graphs generalize (reflexive) interval graphs and those (irreflexive) bipartite graphs whose complements are circular arc graphs. They are relevant for the so-called list homomorphism problem: when H is a bi-arc graph, the problem is polynomial time solvable, otherwise it is NP-complete. Bi-arc graphs have a forbidden structure characterization, and can be recognized in polynomial time. More importantly for this paper, bi-arc graphs can be characterized by the existence of a conservative majority function. (This function plays an important role in proving the correctness of a polynomial time list homomorphism algorithm.) The forbidden structure theorem for bi-arc graphs is quite complex, and the existence of a conservative majority function is proved without giving an explicit description of it. In this note we focus on bi-arc graphs that are trees (with loops allowed). We describe the structure of bi-arc trees, and give a simple forbidden subtree characterization. Based on this structure theorem, we are able to explicitly describe the conservative majority functions.
Year
DOI
Venue
2007
10.1016/j.disc.2005.09.031
Discrete Mathematics
Keywords
Field
DocType
list homomorphism,circular arc graph,homomorphism,majority function,forbidden subgraph characterization,bi-arc graph,bi-arc tree,polynomial time,bipartite graph,interval graph
Discrete mathematics,Indifference graph,Combinatorics,Forbidden graph characterization,Robertson–Seymour theorem,Chordal graph,Cograph,Pathwidth,1-planar graph,Mathematics,Strong perfect graph theorem
Journal
Volume
Issue
ISSN
307
3-5
Discrete Mathematics
Citations 
PageRank 
References 
0
0.34
6
Authors
3
Name
Order
Citations
PageRank
Tomás Feder11959184.99
Pavol Hell22638288.75
Jing Huang32464186.09