A presentation for the planar pure braid group

Abstract

We describe the construction of a minimal presentation for the group of planar pure braids $\overline{P}_n$ on $n$ strands. The generators of this presentation are dual to the generators of the cohomology ring of $\overline{P}_n$ found by Y.Baryshnikov while the relations lie in the commutator subgroup of $\overline{P}_n$. We also construct an explicit (although non-minimal) presentation for the pure cactus group.