Equipopularity Classes in the Separable Permutations

Michael Albert, Cheyne Homberger, Jay Pantone

Published 2014-10-27Version 1

When two patterns occur equally often in a set of permutations, we say that these patterns are equipopular. Using both structural and analytic tools, we classify the equipopular patterns in the set of separable permutations. In particular, we show that the number of equipopularity classes for length $n$ patterns in the separable permutations is equal to the number of partitions of $n-1$.