Longest uncrossed knight's path

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The longest uncrossed (or nonintersecting) knight's path is a mathematical problem involving a knight on the standard 8×8 chessboard or, more generally, on a square n×n board. The problem is to find the longest path the knight can take on the given board, such that the path does not intersect itself. A further distinction can be made between a closed path, which ends on the same field as where it begins, and an open path, which ends on a different field from where it begins.

Contents

[edit] Known solutions

The longest open paths are known only for n ≤ 9. Their lengths for n = 1, 2, …, 9 are:

0, 0, 2, 5, 10, 17, 24, 35, 47 (sequence A003192 in OEIS)

The longest closed paths are known only for n ≤ 10. Their lengths for n = 1, 2, …, 10 are:

0, 0, 0, 4, 8, 12, 24, 32, 42, 54 (sequence A157416 in OEIS)
UncrossedKnightsPath7x7.svg UncrossedKnightsPath8x8.svg
A longest closed path for n = 7
of length 24.
A longest open path for n = 8
of length 35.

[edit] Generalizations

The problem can be further generalized to rectangular n×m boards, or even to boards in the shape of any polyomino. Other standard chess pieces than the knight are less interesting, but fairy chess pieces like camel, giraffe and zebra lead to problems of comparable complexity.

[edit] See also

  • A knight's tour is a self-intersecting knight's path visiting all fields of the board.
  • TwixT, a board game based on uncrossed knight's paths.

[edit] References

[edit] External links

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