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Counting Knight's Tours through the Randomized Warnsdorff Rule

Héctor Cancela·Ernesto Mordecki
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Abstract

We give an estimate of the number of geometrically distinct open tours $\G$ for a knight on a chessboard. We use a randomization of Warnsdorff rule to implement importance sampling in a backtracking scheme, correcting the observed bias of the original rule, according to the proposed principle that ``most solutions follow Warnsdorff rule most of the time''. After some experiments in order to test this principle, and to calibrate a parameter, interpreted as a distance of a general solution from a Warnsdorff solution, we conjecture that $\G=1.22\times 10^{15}$.

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Héctor Cancela, Ernesto Mordecki. 2006-08-31. Counting Knight's Tours through the Randomized Warnsdorff Rule. https://arxiv.org/abs/math/0609009

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