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Complexity of locally-injective homomorphisms to tournaments

Authors :
Stefan Bard
Thomas Bellitto
Christopher Duffy
Gary MacGillivray
Feiran Yang
Source :
Discrete Mathematics & Theoretical Computer Science, Vol vol. 20 no. 2, Iss Graph Theory (2018)
Publication Year :
2018
Publisher :
Discrete Mathematics & Theoretical Computer Science, 2018.

Abstract

For oriented graphs $G$ and $H$, a homomorphism $f: G \rightarrow H$ is locally-injective if, for every $v \in V(G)$, it is injective when restricted to some combination of the in-neighbourhood and out-neighbourhood of $v$. Two of the possible definitions of local-injectivity are examined. In each case it is shown that the associated homomorphism problem is NP-complete when $H$ is a reflexive tournament on three or more vertices with a loop at every vertex, and solvable in polynomial time when $H$ is a reflexive tournament on two or fewer vertices.

Details

Language :
English
ISSN :
13658050
Volume :
. 20
Issue :
Graph Theory
Database :
Directory of Open Access Journals
Journal :
Discrete Mathematics & Theoretical Computer Science
Publication Type :
Academic Journal
Accession number :
edsdoj.424b954e2ea44308a0d7c0d8951ce4f7
Document Type :
article
Full Text :
https://doi.org/10.23638/DMTCS-20-2-4