Optimization problems in multiple subtree graphs Original Research Article

We study various optimization problems in t-subtree graphs, the intersection graphs of image-subtrees, where a image-subtree is the union of image disjoint subtrees of some tree. This graph class generalizes both the class of chordal graphs and the class of image-interval graphs, a generalization of interval graphs that has recently been studied from a combinatorial optimization point of view. We present approximation algorithms for the Maximum Independent Set, Minimum Coloring, Minimum Vertex Cover, Minimum Dominating Set, and Maximum Clique problems.