Tight lower and upper bounds for some distributed algorithms for a complete network of processors

  • Authors:

  • E. Korach;S. Moran;S. Zaks

  • Affiliations:

  • -;-;-

  • Venue:
  • PODC '84 Proceedings of the third annual ACM symposium on Principles of distributed computing
  • Year:
  • 1984

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Abstract

Distributed algorithms for complete asynchronous networks of processors (i.e., networks where each pair of processors is connected by a communication line) are discussed. The main result is O(nlogn) lower and upper bounds on the number of messages required by any algorithm in a given class of distributed algorithms for such networks. This class includes algorithms for problems like finding a leader or constructing a spanning tree (as far as we know, all known algorithms for those problems may require O(n2) messages when applied to complete networks). O(n2) bounds for other problems, like constructing a maximal matching or a Hamiltonian circuit are also given. In proving the lower bound we are counting the edges which carry messages during the executions of the algorithms (ignoring the actually number of messages carried by each edge). Interestingly, this number is shown to be of the same order of magnitude of the total number of messages needed by these algorithms. In the upper bounds, the length of any message is at most log2[4mlog2n] bits, where m is the maximum identity of a node in the network. One implication of our results is that finding a spanning tree in a complete network is easier than finding a minimum weight spanning tree in such a network, which may require O(n2) messages.