Approximation algorithms for the maximum weight internal spanning tree problem

Abstract

Given a vertex-weighted connected graph $G=(V,E)$, the maximum weight internal spanning tree (MwIST for short) problem asks for a spanning tree $T$ of $G$ such that the total weight of the internal vertices in $T$ is maximized. The un-weighted variant, denoted as MIST, is NP-hard and APX-hard, and the currently best approximation algorithm has a proven performance ratio $13/17$. The currently best approximation algorithm for MwIST only has a performance ratio $1/3-\hat{I}\mu$, for any $\hat{I}\mu >0$. In this paper, we present a simple algorithm based on a novel relationship between MwIST and the maximum weight matching, and show that it achieves a better approximation ratio of $1/2$. When restricted to claw-free graphs, a special case been previously studied, we design a $7/12$-approximation algorithm.

Revised complete version, with 27 pages, 27 figures; an extended abstract appears in the Proceedings of COCOON 2017