Improved Approximation Algorithms for the Expanding Search Problem

SIAM Journal on Discrete Mathematics, vol. 40, pp. 349–373

Abstract

Abstract. A searcher is tasked with exploring a graph with edge lengths and vertex weights, starting from a designated vertex. Initially, only the starting vertex is considered explored. At each step, the searcher adds an edge to the solution, connecting an unexplored vertex to an explored one. The time required to add an edge equals its length. The objective is to minimize the weighted sum of exploration times for all vertices. We demonstrate that this problem is hard to approximate and present algorithms with improved approximation guarantees. Specifically, we provide a [Formula: see text]-approximation for any [Formula: see text] for the general case. On instances where the vertex weights are binary, we achieve a [Formula: see text]-approximation. Finally, we develop a polynomial-time approximation scheme for Euclidean graphs. Previously, only an 8-approximation was known for all these cases.

Authors 0

1. Author list not loaded yet.