
Article
Quasi-platonic PSL2(q)-actions on closed Riemann surfaces
Mathematical Sciences Technical Reports (MSTR)
(2015)
Abstract
This paper is the first of two papers whose combined goal is to explore the dessins d'enfant and symmetries of quasi-platonic actions of PSL2(q). A quasi-platonic action of a group G on a closed Riemann S surface is a conformal action for which S/G is a sphere and S->S/G is branched over {0, 1,infinity}. The unit interval in S/G may be lifted to a dessin d'enfant D, an embedded bipartite graph in S. The dessin forms the edges and vertices of a tiling on S by dihedrally symmetric polygons, generalizing the idea of a platonic solid. Each automorphism p in the absolute Galois group determines a transform Sp by transforming the coefficients of the defining equations of S. The transform defines a possibly new quasi-platonic action and a transformed dessin Dp. Here, in this paper, we describe the quasi-platonic actions of PSL2(q) and the action of the absolute Galois group on PSL2(q) actions. The second paper discusses the quasi-platonic actions constructed from symmetries (reflections) and the resulting triangular tiling that refines the dessin d'enfant. In particular, the number of ovals and the separation properties of the mirrors of a symmetry are determined.
Keywords
- Riemann surface,
- quasi-platonic surface,
- automorphism group,
- symmetries. 2
Disciplines
Publication Date
December 2, 2015
Publisher Statement
MSTR 15-01
Subsequently published in Albanian Journal of Mathemtics
Citation Information
Sean A Broughton. "Quasi-platonic PSL2(q)-actions on closed Riemann surfaces" Mathematical Sciences Technical Reports (MSTR) (2015) Available at: http://works.bepress.com/allen_broughton/35/