Optimal distributed algorithms for minimum weight spanning tree, counting, leader election, and related problems

This paper develops linear time distributed algorithms for a class of problems in an asynchronous communication network. Those problems include Minimum-Weight Spanning Tree (MST), Leader Election, counting the number of network nodes, and computing a sensitive decomposable function (e.g. majority, parity, maximum, OR, AND). The main problem considered is the problem of finding the MST. This problem, which has been known for at least 9 years, is one of the most fundamental and the most studied problems in the field of distributed network algorithms. Any algorithm for any one of the problems above requires at least &OHgr;(E + VlogV) communication and &OHgr;(V) time in the general network. In this paper, we present new algorithms, which achieve those lower bounds. The best previous algorithm requires &THgr;(E + VlogV) in communication and &THgr;(V log V) in time. Our result enables to improve algorithms for many other problems in distributed computing, achieving lower bounds on their communication and time complexities.