English

The Infinite Sphere and Galois Belyi maps

Algebraic Geometry 2026-02-13 v1 Number Theory

Abstract

We show that the space of Belyi maps admits a natural parametrization by an infinite-dimensional sphere arising from Voiculescu's theory of noncommutative probability spaces. We show that this sphere decomposes into sectors, each of which corresponds to a class of Belyi maps distinguished up to isomorphism by their monodromy, encoded by a finite-index subgroup of F2. For Galois Belyi maps, our correspondence between spectral sectors of the infinite sphere and algebraic quotients of F2 yields a genuine bijection. Within this framework, distinct sectors of the sphere capture the algebraic constraints imposed on the monodromy, thereby providing a geometric organization of Belyi maps according to their associated group-theoretic data.

Keywords

Cite

@article{arxiv.2602.11778,
  title  = {The Infinite Sphere and Galois Belyi maps},
  author = {Noémie C. Combe},
  journal= {arXiv preprint arXiv:2602.11778},
  year   = {2026}
}