Algebraic structures defined on $m$-Dyck paths

Abstract

We introduce natural binary set-theoretical products on the set of all $m$-Dyck paths, which led us to define a non-symmetric algebraic operad $\Dy^m$, described on the vector space spanned by $m$-Dyck paths. Our construction is closely related to the $m$-Tamari lattice, so the products defining $\Dy^m$ are given by intervals in this lattice. For $m=1$, we recover the notion of dendriform algebra introduced by J.-L. Loday in \cite{Lod}, and there exists a natural operad morphism from the operad ${\mbox {\it Ass}}$ of associative algebras into the operad $\Dy^m$, consequently $\Dy ^m$ is a Hopf operad. We give a description of the coproduct in terms of $m$-Dyck paths in the last section. As an additional result, for any composition of $m+1\geq 2$ with $r+1$ parts, we get a functor from the category of $\Dy ^m$ algebras into the category of $\Dy ^r$ algebras.