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arXiv · 1404.0948

The Quest for Optimal Sorting Networks: Efficient Generation of Two-Layer Prefixes

Michael Codish·Luis Cruz-Filipe·Peter Schneider-Kamp
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Abstract

Previous work identifying depth-optimal $n$-channel sorting networks for $9\leq n \leq 16$ is based on exploiting symmetries of the first two layers. However, the naive generate-and-test approach typically applied does not scale. This paper revisits the problem of generating two-layer prefixes modulo symmetries. An improved notion of symmetry is provided and a novel technique based on regular languages and graph isomorphism is shown to generate the set of non-symmetric representations. An empirical evaluation demonstrates that the new method outperforms the generate-and-test approach by orders of magnitude and easily scales until $n=40$.

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Michael Codish, Luis Cruz-Filipe, Peter Schneider-Kamp. 2014-04-03. The Quest for Optimal Sorting Networks: Efficient Generation of Two-Layer Prefixes. https://doi.org/10.1109/synasc.2014.55

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