English

An Expansion Formula for Decorated Super-Teichm\"uller Spaces

Combinatorics 2021-09-02 v3

Abstract

Motivated by the definition of super-Teichm\"uller spaces, and Penner-Zeitlin's recent extension of this definition to decorated super-Teichm\"uller space, as examples of super Riemann surfaces, we use the super Ptolemy relations to obtain formulas for super λ\lambda-lengths associated to arcs in a bordered surface. In the special case of a disk, we are able to give combinatorial expansion formulas for the super λ\lambda-lengths associated to diagonals of a polygon in the spirit of Ralf Schiffler's TT-path formulas for type AA cluster algebras. We further connect our formulas to the super-friezes of Morier-Genoud, Ovsienko, and Tabachnikov, and obtain partial progress towards defining super cluster algebras of type AnA_n. In particular, following Penner-Zeitlin, we are able to get formulas (up to signs) for the μ\mu-invariants associated to triangles in a triangulated polygon, and explain how these provide a step towards understanding odd variables of a super cluster algebra.

Keywords

Cite

@article{arxiv.2102.09143,
  title  = {An Expansion Formula for Decorated Super-Teichm\"uller Spaces},
  author = {Gregg Musiker and Nicholas Ovenhouse and Sylvester W. Zhang},
  journal= {arXiv preprint arXiv:2102.09143},
  year   = {2021}
}
R2 v1 2026-06-23T23:16:29.599Z