Recovering trees from the cohomology ring of their configuration spaces

Abstract

Given a tree $T$, the cohomology ring of its unordered configuration space $H^{\ast }(U{\mathcal{D}}^{n}T)$ is an exterior face algebra if $T$ is a binary core tree (if by removing the leaves from $T$ we obtain a binary tree), or if $n=4$. This means that every cup product is determined by a simplicial complex $K_{n}T$. In this paper we show how to recover the tree $T$ from the simplicial complex $K_{n}T$ when $n=4.$