30 citations · 80 across the 23 of their papers we have counts for
26 papers · 1 filter
Protected tails and polynomial-time enumeration of permutations avoiding a direct sum of an increasing pattern and 231
Henning Ulfarsson, Henning Arnór Skeggi Úlfarsson
We give an algorithm counting the permutations that avoid a fixed pattern of the following form: the direct sum of an increasing pattern and 231. The first members of the family ar…
Inversion monotonicity in subclasses of the 1324-avoiders
Anders Claesson, Svante Linusson, Henning Ulfarsson +1
A collection of patterns is called inversion monotone if , the number of -avoiding permutations of length with inversions, is weakly increasing i…
A Permutation Avoidance Game with Reverse Replies and Monotone Traps
Henning Ulfarsson
We study the impartial game PAP (``permutations avoiding patterns''), in which players take turns choosing patterns to avoid. We define a set of length patterns, , and sho…
BiSC: An algorithm for discovering generalized permutation patterns
Henning Ulfarsson
Theorems relating permutations with objects in other fields of mathematics are often stated in terms of avoided patterns. Examples include various classes of Schubert varieties fro…
Permutations avoiding bipartite partially ordered patterns have a regular insertion encoding
Christian Bean, Émile Nadeau, Jay Pantone +1
We prove that any class of permutations defined by avoiding a partially ordered pattern (POP) with height at most two has a regular insertion encoding and thus has a rational gener…
Turning cycle restrictions into mesh patterns via Foata's fundamental transformation
Anders Claesson, Henning Ulfarsson
An adjacent -cycle is a natural generalization of an adjacent transposition. We show that the number of adjacent -cycles in a permutation maps to the sum of occurrences of tw…