Anonymous Processors with Synchronous Shared Memory: Monte Carlo Algorithms

摘要

We consider synchronous distributed systems in which processors communicate by shared read- write variables. Processors are anonymous and do not know their number n. The goal is to assign individual names by all the processors to themselves. We develop algorithms that accomplish this for each of the four cases determined by the following independent properties of the model: concurrently attempting to write distinct values into the same shared memory register either is allowed or not, and the number of shared variables either is a constant or it is unbounded. For each such a case, we give a Monte Carlo algorithm that runs in the optimum expected time and uses the expected number of O(n log n) random bits. All our algorithms produce correct output upon termination with probabilities that are 1?n^{?Ω(1)}, which is best possible when terminating almost surely and using O(n log n) random bits.