Minimum latency tours and the k-traveling repairmen problem

Given an undirected graph G = (V, E) and a source vertex s is an element of V, the k-traveling repairman (KTR) problem, also known as the minimum latency problem, asks for k tours, each starting at s and covering all the vertices (customers) such that the sum of the latencies experienced by the customers is minimum. Latency of a customer p is defined to be the distance (time) traveled before visiting p for the first time. Previous literature on the KTR problem has considered the version of the problem in which the repairtime of a customer is assumed to be zero for latency calculations. We consider a generalization of the problem in which each customer has an associated repairtime. In this paper, we present constant factor approximation algorithms for this problem and its variants.