Random monotone factorisations of the cycle

Abstract

In this article we study decreasing and increasing factorisations of the cycle, which are decompositions of the cycle $(12\dots n)$ into a product of $n-1$ transpositions satisfying monotonicity conditions. We explicit a bijection between such factorisations and plane trees with $n$ vertices. This will allow us to study some of their combinatorial properties, as well as a geometric representation in terms of laminations, which are non-crossing line segments in the unit disk.

19 pages, 9 figures