Improved routing and sorting on multibutterflies
STOC '97 Proceedings of the twenty-ninth annual ACM symposium on Theory of computing
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We define a distributed selection game that generalizes a selection problem considered by S.R. Kosaraju (1989). We offer a tight analysis of our distributed selection game, and show that the lower bound for this abstract communication game directly implies near-tight lower bounds for certain selection problems on fixed-connection machines. For example, we prove that any deterministic comparison-based selection algorithm on an (n/log n)-processor bounded-degree hypercubic machine requires /spl Omega/(log/sup 3/2/n) steps in the worst case. This lower bound implies a non-trivial separation between the power of bounded-degree hypercubic and expander-based machines. Furthermore, we show that the algorithm underlying our tight upper bound for the distributed selection game can be adapted to run in O((log/sup 3/2/n) (log log n)/sup 2/) steps on any (n/log n)-processor hypercubic machine.