On cliques of Helly Circular-arc Graphs

A circular-arc graph is the intersection graph of a set of arcs on the circle. It is a Helly circular-arc graph if it has a Helly model, where every maximal clique is the set of arcs that traverse some clique point on the circle. A clique model is a Helly model that identifies one clique point for each maximal clique. A Helly circular-arc graph is proper if it has a Helly model where no arc is a subset of another. In this paper, we show that the clique intersection graphs of Helly circular-arc graphs are related to the proper Helly circular-arc graphs. This yields the first polynomial (linear) time recognition algorithm for the clique graphs of Helly circular-arc graphs. Next, we develop an O(n) time algorithm to obtain a clique model of Helly model, improving the previous O(n2) bound. This gives a linear-time algorithm to find a proper Helly model for the clique graph of a Helly circular-arc graph. As an application, we find a maximum weighted clique of a Helly circular-arc graph in ...

• Type: Journal
• Year: 2008
• Where: ENDM
• Authors: Min Chih Lin, Ross M. McConnell, Francisco J. Soulignac, Jayme Luiz Szwarcfiter
• Keywords: Clique, ENDM 2008, Helly Circular-arc Graph, Helly Model