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arXiv · 2012.04400

An Answer to the Bose-Nelson Sorting Problem for 11 and 12 Channels

Jannis Harder
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Abstract

We show that 11-channel sorting networks have at least 35 comparators and that 12-channel sorting networks have at least 39 comparators. This positively settles the optimality of the corresponding sorting networks given in The Art of Computer Programming vol. 3 and closes the two smallest open instances of the Bose-Nelson sorting problem. We obtain these bounds by generalizing a result of Van Voorhis from sorting networks to a more general class of comparator networks. From this we derive a dynamic programming algorithm that computes the optimal size for a sorting network with a given number of channels. From an execution of this algorithm we construct a certificate containing a derivation of the corresponding lower size bound, which we check using a program formally verified using the Isabelle/HOL proof assistant.

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Jannis Harder. 2020-12-08. An Answer to the Bose-Nelson Sorting Problem for 11 and 12 Channels. https://arxiv.org/abs/2012.04400

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