Avoiding permutation patterns of type (2, 1) in compositions

Silvia Heubach 1, Toufik Mansour 2, Augustine O. Munagi 3
1Department of Mathematics, California State University Los Angeles, Los Angeles, CA 90032
2Department of Mathematics, University of Haifa, Haifa 31905, Israel
3School of Mathematics, University of the Witwatersrand, 2050 Johannesburg, South Africa

Abstract

We classify compositions avoiding a single permutation pattern of type (2, 1) according to
Wilf-equivalence and give the generating function for each of the Wilf classes.

Keywords: Pattern avoidance, compositions, Wilf-equivalence, generating functions