k-Gap Interval Graphs

TL;DR

This paper introduces k-gap interval graphs, a new graph class based on multiple interval representations, and develops fixed-parameter tractable algorithms for several classical problems within this class.

Contribution

It defines k-gap interval graphs and provides FPT algorithms for problems like Feedback Vertex Set, Dominating Set, and others, extending interval graph properties.

Findings

FPT algorithms for Feedback Vertex Set, Dominating Set, Independent Set, Clique, Clique Cover, and Multiple Interval Transversal.

Coloring problem is W[1]-hard on k-gap interval graphs.

Recognition problem admits an XP algorithm.

Abstract

We initiate the study of a new parameterization of graph problems. In a multiple interval representation of a graph, each vertex is associated to at least one interval of the real line, with an edge between two vertices if and only if an interval associated to one vertex has a nonempty intersection with an interval associated to the other vertex. A graph on n vertices is a k-gap interval graph if it has a multiple interval representation with at most n+k intervals in total. In order to scale up the nice algorithmic properties of interval graphs (where k=0), we parameterize graph problems by k, and find FPT algorithms for several problems, including Feedback Vertex Set, Dominating Set, Independent Set, Clique, Clique Cover, and Multiple Interval Transversal. The Coloring problem turns out to be W[1]-hard and we design an XP algorithm for the recognition problem.