English

Trees and cycles

Combinatorics 2020-10-29 v1

Abstract

Let TT be a tree on nn vertices. We can regard the edges of TT as transpositions of the vertex set; their product (in any order) is a cyclic permutation. All possible cyclic permutations arise (each exactly once) if and only if the tree is a star. In this paper we find the number of realised cycles, and obtain some results on the number of realisations of each cycle, for other trees. We also solve the inverse problem of the number of trees which give rise to a given cycle. On the way, we meet some familiar number sequences including the Euler and Fuss--Catalan numbers.

Keywords

Cite

@article{arxiv.2010.14902,
  title  = {Trees and cycles},
  author = {Peter J. Cameron and Liam Stott},
  journal= {arXiv preprint arXiv:2010.14902},
  year   = {2020}
}

Comments

34 pages, 7 figures and 1 table