English

Penney's game for permutations

Combinatorics 2026-04-29 v3

Abstract

We consider the permutation analogue of Penney's game for words. Two players, in order, each choose a permutation of length k3k\ge3; then a sequence of independent random values from a continuous distribution is generated, until the relative order of the last kk numbers coincides with one of the chosen permutations, making that player the winner. We compute the winning probabilities for all pairs of permutations of length 3 and some pairs of length 4, showing that, as in the original version for words, the game is non-transitive. Our proofs introduce new bijections for consecutive patterns in permutations. We also give some formulas to compute the winning probabilities more generally, and conjecture a winning strategy for the second player when kk is arbitrary.

Keywords

Cite

@article{arxiv.2404.06585,
  title  = {Penney's game for permutations},
  author = {Sergi Elizalde and Yixin Lin},
  journal= {arXiv preprint arXiv:2404.06585},
  year   = {2026}
}
R2 v1 2026-06-28T15:49:15.691Z