Complexity of Paired Domination in AT-free and Planar Graphs

TL;DR

This paper investigates the complexity of the paired domination problem, providing a polynomial-time solution for AT-free graphs and proving NP-completeness for planar graphs, thus clarifying the problem's computational boundaries.

Contribution

It introduces a polynomial-time algorithm for minimum paired domination in AT-free graphs and establishes NP-completeness for planar graphs, resolving open questions in the field.

Findings

Polynomial-time algorithm for AT-free graphs

Linear 2-approximation algorithm for AT-free graphs

NP-completeness of the problem in planar graphs

Abstract

For a graph $G=(V,E)$, a subset $D$ of vertex set $V$, is a dominating set of $G$ if every vertex not in $D$ is adjacent to atleast one vertex of $D$. A dominating set $D$ of a graph $G$ with no isolated vertices is called a paired dominating set (PD-set), if $G[D]$, the subgraph induced by $D$ in $G$ has a perfect matching. The Min-PD problem requires to compute a PD-set of minimum cardinality. The decision version of the Min-PD problem remains NP-complete even when $G$ belongs to restricted graph classes such as bipartite graphs, chordal graphs etc. On the positive side, the problem is efficiently solvable for many graph classes including intervals graphs, strongly chordal graphs, permutation graphs etc. In this paper, we study the complexity of the problem in AT-free graphs and planar graph. The class of AT-free graphs contains cocomparability graphs, permutation graphs, trapezoid graphs, and interval graphs as subclasses. We propose a polynomial-time algorithm to compute a minimum PD-set in AT-free graphs. In addition, we also present a linear-time $2$-approximation algorithm for the problem in AT-free graphs. Further, we prove that the decision version of the problem is NP-complete for planar graphs, which answers an open question asked by Lin et al. (in Theor. Comput. Sci., $591 (2015): 99-105$ and Algorithmica, $ 82 (2020) :2809-2840$).