Queen reflections

a modification of Wythoff Nim

Journal Article (2022)
Author(s)

Robbert Fokkink (TU Delft - Applied Probability, Open University of the Netherlands)

Research Group
Applied Probability
Copyright
© 2022 R.J. Fokkink
DOI related publication
https://doi.org/10.1007/s00182-022-00824-1
More Info
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Publication Year
2022
Language
English
Copyright
© 2022 R.J. Fokkink
Research Group
Applied Probability
Issue number
4
Volume number
53
Pages (from-to)
1099-1117
Reuse Rights

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Abstract

Wythoff Nim is a classical combinatorial game of queen moves on a chessboard. There are many ways to describe its P-positions (safe positions to move to). One way is to code them by the Fibonacci word 010010100100101.., which is the unique fixed point of the substitution of 0 by 01, and of 1 by 0. The coordinates of the n-th P-position are encoded by the location of the n-th zero and the n-th one in the Fibonacci word. We show that a minor modification of the rules of Wythoff Nim leads to a game with P-positions that are coded by 010010010010100100.. This word can be derived by deleting all 2’s from the Tribonacci word, which is the unique fixed point of the substitution of 0 by 01, of 1 by 02, and of 2 by 0.