English

Perfect $1$-factorisations of $K_{11,11}$

Combinatorics 2026-04-10 v2

Abstract

A perfect 11-factorisation of a graph is a decomposition of that graph into 11-factors such that the union of any two 11-factors is a Hamiltonian cycle. A Latin square of order nn is row-Hamiltonian if for every pair (r,s)(r,s) of distinct rows, the permutation mapping rr to ss has a single cycle of length nn. We report the results of a computer enumeration of the perfect 11-factorisations of the complete bipartite graph K11,11K_{11,11}. This also allows us to find all row-Hamiltonian Latin squares of order 1111. Finally, we plug a gap in the literature regarding how many row-Hamiltonian Latin squares are associated with the classical families of perfect 11-factorisations of complete graphs.

Cite

@article{arxiv.2506.02455,
  title  = {Perfect $1$-factorisations of $K_{11,11}$},
  author = {Jack Allsop and Ian M. Wanless},
  journal= {arXiv preprint arXiv:2506.02455},
  year   = {2026}
}
R2 v1 2026-07-01T02:55:56.456Z