Symmetric and asymmetric peaks in compositions

Abstract

Integer compositions and related counting problems are a rich and ubiquitous topic in enumerative combinatorics. In this paper we explore the definition of symmetric and asymmetric peaks and valleys over compositions. In particular, we compute an explicit formula for the generating function for the number of integer compositions according to the number of parts, symmetric, and asymmetric peaks and valleys.

Keywords: Compositions, peaks, symmetric peaks, asymmetric peaks, generating functions.