# Contents

## Idea

The notion of dendrex is the operadic analog of the notion of simplex.

## Definition

For $X$ a dendroidal set and $T$ a tree, a $T$-shaped dendrex of $X$ is a morphism

$\Omega \left[T\right]\to X\phantom{\rule{thinmathspace}{0ex}},$\Omega[T] \to X \,,

hence equivalently, by the Yoneda lemma, an element of the set $X\left(T\right)$.