English

The Combinatorics of Directed Planar Trees

Combinatorics 2017-04-20 v1 Geometric Topology Quantum Algebra

Abstract

We give a geometric realization of the polyhedra governed by the structure of associative algebras with co-inner products, or more precisely, governed by directed planar trees. Our explicit realization of these polyhedra, which include the associahedra in a special case, shows in particular that these polyhedra are homeomorphic to balls. We also calculate the number of vertices of the lowest generalized associahedra, giving appropriate generalizations of the Catalan numbers.

Keywords

Cite

@article{arxiv.1704.05557,
  title  = {The Combinatorics of Directed Planar Trees},
  author = {Kate Poirier and Thomas Tradler},
  journal= {arXiv preprint arXiv:1704.05557},
  year   = {2017}
}

Comments

30 pages, 21 figures

R2 v1 2026-06-22T19:20:46.540Z