Computing role assignments of proper interval graphs in polynomial time

Pinar Heggernes, Pim van 't Hof, Daniël Paulusma

Research output: Contribution to journalConference articleAcademicpeer-review

10 Citations (Scopus)


An R-role assignment of a graph G is a locally surjective homomorphism from G to graph R. For a fixed graph R, the R-Role Assignment problem is to decide, for an input graph G, whether G has an R-role assignment. When both graphs G and R are given as input, the problem is called Role Assignment. In this paper, we study the latter problem. It is known that R-Role Assignment is -complete already when R is a path on three vertices. In order to obtain polynomial time algorithms for Role Assignment, it is therefore necessary to put restrictions on G. So far, the only known non-trivial case for which this problem is solvable in polynomial time is when G is a tree. We present an algorithm that solves Role Assignment in polynomial time when G is a proper interval graph. Thus we identify the first graph class other than trees on which the problem is tractable. As a complementary result, we show that Role Assignment is Graph Isomorphism-hard on chordal graphs, a superclass of proper interval graphs and trees.
Original languageEnglish
Pages (from-to)173-188
Number of pages16
JournalJournal of discrete algorithms
Publication statusPublished - 2012
Externally publishedYes
Event21st International Workshop on Combinatorial Algorithms, IWOCA 2010 - London, United Kingdom
Duration: 26 Jul 201028 Jul 2010
Conference number: 21


Dive into the research topics of 'Computing role assignments of proper interval graphs in polynomial time'. Together they form a unique fingerprint.

Cite this