Title
Edge contractions in subclasses of chordal graphs
Abstract
Modifying a given graph to obtain another graph is a wellstudied problem with applications in many fields. Given two input graphs G and H, the Contractibility problem is to decide whether H can be obtained from G by a sequence of edge contractions. This problem is known to be NP-complete already when both input graphs are trees of bounded diameter. We prove that CONTRACTIBILITY can be solved in polynomial time when G is a trivially perfect graph and H is a threshold graph, thereby giving the first classes of graphs of unbounded treewidth and unbounded degree on which the problem can be solved in polynomial time. We show that this polynomial-time result is in a sense tight, by proving that Contractibility is NP-complete when G and H are both trivially perfect graphs, and when G is a split graph and H is a threshold graph. If the graph H is fixed and only G is given as input, then the problem is called H-CONTRACTIBILITY. This problem is known to be NP-complete on general graphs already when H is a path on four vertices. We show that, for any fixed graph H, the H-CONTRACTIBILITY problem can be solved in polynomial time if the input graph G is a split graph.
Year
DOI
Venue
2012
10.1016/j.dam.2011.12.012
Discrete Applied Mathematics
Keywords
Field
DocType
induced subgraph isomorphism
Discrete mathematics,Block graph,Combinatorics,Line graph,Threshold graph,Distance-hereditary graph,Trivially perfect graph,Symmetric graph,Pathwidth,Mathematics,Split graph
Journal
Volume
Issue
ISSN
160
7-8
0166-218X
Citations 
PageRank 
References 
15
0.80
17
Authors
3
Name
Order
Citations
PageRank
Rémy Belmonte17411.76
Pinar Heggernes284572.39
Pim van 't Hof320920.75