Dominating induced matchings in [formula omitted]-free graphs

Abstract

Let G=(V,E) be a finite undirected graph without loops and multiple edges. A subset M⊆E of edges is a dominating induced matching (d.i.m. ) in G if every edge in E is intersected by exactly one edge of M. In particular, this means that M is an induced matching, and every edge not in M shares exactly one vertex with an edge in M. Clearly, not every graph has a d.i.m.The Dominating Induced Matching (DIM) problem asks for the existence of a d.i.m. in G; this problem is also known as the Efficient Edge Domination problem; it is the Efficient Domination problem for line graphs.The DIM problem is NP-complete in general, and even for very restricted graph classes such as planar bipartite graphs with maximum degree 3. However, DIM is solvable in polynomial time for claw-free (i.e., S1,1,1-free) graphs, for S1,2,3-free graphs, for S2,2,2-free graphs as well as for S2,2,3-free graphs, in linear time for P7-free graphs, and in polynomial time for P8-free graphs (Pk is a special case of Si,j,ℓ). In a paper by Hertz, Lozin, Ries, Zamaraev and de Werra, it was conjectured that DIM is solvable in polynomial time for Si,j,k-free graphs for every fixed i,j,k.In this paper, combining two distinct approaches, we solve it in polynomial time for S1,2,4-free graphs which generalizes the S1,2,3-free as well as the P7-free case.