Toufik Mansour

Enumeration of 3- and 4-Wilf classes of four 4-letter patterns

2018 · Notes on Number Theory and Discrete Mathematics

Let be the symmetric group of all permutations of letters. We show that there are precisely 27 (respectively, 15) Wilf classes consisting of exactly 3 (respectively, 4) symmetry classes of subsets of four 4-letter patterns.