Brief Announcement: Distributed Single-Source Reachability

In the directed single-source reachability problem, input is a directed graph G = (V,E) and a source s is an element of V, and the objective is to identify nodes t for which there is a directed path in G from s to t. Recently Nanongkai [2] presented a distributed algorithm that solves this problem in (O) over tilde (D + root nD(1/2)) rounds, where D and n respectively denote the network diameter and the number of nodes. This note presents an algorithm that improves the round complexity to (O) over tilde (D + root nD(1/4)), thus getting closer to the (Omega) over tilde (D + root n) lower bound of Das Sarma et al. [1].