Georgia Institute of Technology College of Sciences

Given a vertex-weighted graph G= (V, E), the MaximumWeight Internal Spanning Tree (MWIST) problem is to find a spanning tree T of G such that the total weight of internal vertices in T is maximized. The unweighted version of this problem, known as Maxi-mum Internal Spanning Tree (MIST) problem, is a generalization of the Hamiltonian path problem, and hence, it is NP-hard. In the literature lot of research has been done on designing approximation algorithms to achieve an approximation ratio close to 1. The best known approximation algorithm achieves an approximation ratio of 17/13 for the MIST problem for general graphs. For the MWIST problem, the current best approximation algorithm achieves an approximation ratio of 2 for general graphs. Researchers have also tried to design exact/approximation algorithms for some special classes of graphs. The MIST problem parameterized by the number of internal vertices k, and its special cases and variants, have also been extensively studied in the literature. The best known kernel for the general problem has size 2k, which leads to the fastest known exact algorithm with running time O(4^kn^{O(1)}). In this talk, we will talk about some selected recent results on the MWIST problem.