English

Naturally emerging maps for derangements and nonderangements

Combinatorics 2023-09-11 v2

Abstract

A derangement is a permutation with no fixed point, and a nonderangement is a permutation with at least one fixed point. There is a one-term recurrence for the number of derangements of nn elements, and we describe a bijective proof of this recurrence which can be found using a recursive map. We then show the combinatorial interpretation of this bijection and how it compares with other known bijections, and show how this gives an involution on Sn\mathfrak{S}_n. Nonderangements satisfy a similar recurrence. We convert the bijective proof of the one-term identity for derangements into a bijective proof of the one-term identity for nonderangements.

Keywords

Cite

@article{arxiv.2301.13718,
  title  = {Naturally emerging maps for derangements and nonderangements},
  author = {Melanie Ferreri},
  journal= {arXiv preprint arXiv:2301.13718},
  year   = {2023}
}

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17 pages