Wilf-collapse in permutation classes having two basis elements of size three

TL;DR

This paper classifies the enumeration sequences of permutation classes with two basis elements of size three and one additional basis element, revealing they are fewer than initially expected.

Contribution

It provides a complete classification of enumeration sequences for a specific class of permutation classes with three basis elements.

Findings

Fewer enumeration sequences than expected for these classes

Complete classification of possible sequences

Insights into the structure of permutation classes with specific basis elements

Abstract

We consider permutation classes having two basis elements of size three and one further basis element. We completely classify the possible enumeration sequences of such classes and demonstrate that there are far fewer of them than might be expected in principle.