English

Volume and lattice points counting for the cyclopermutohedron

Metric Geometry 2015-05-05 v1

Abstract

The face lattice of the permutohedron realizes the combinatorics of linearly ordered partitions of the set [n]={1,...,n}[n]=\{1,...,n\}. Similarly, the cyclopermutohedron is a virtual polytope that realizes the combinatorics of cyclically ordered partitions of [n][n]. It is known that the volume of the standard permutohedron equals the number of trees with nn labeled vertices multiplied by n\sqrt{n}. The number of integer points of the standard permutohedron equals the number of forests on nn labeled vertices. In the paper we prove that the volume of the cyclopermutohedron also equals some weighted number of forests, which eventually reduces to zero. We also derive a combinatorial formula for the number of integer points in the cyclopermutohedron. Another object of the paper is the configuration space of a polygonal linkage LL. It has a cell decomposition K(L)\mathcal{K}(L) related to the face lattice of cyclopermutohedron. Using this relationship, we introduce and compute the volume Vol(K(L))Vol(\mathcal{K}(L)).

Keywords

Cite

@article{arxiv.1505.00352,
  title  = {Volume and lattice points counting for the cyclopermutohedron},
  author = {Ilya Nekrasov and Gaiane Panina},
  journal= {arXiv preprint arXiv:1505.00352},
  year   = {2015}
}
R2 v1 2026-06-22T09:27:02.857Z