Coordenadas Fricke e empacotamentos hiperbolicos de discos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

This work searches elements to determine the packing density of spheres defined by lattices in the hyperbolic plane. We consider the teichmüller space Tg of all closed compacts oriented surfaces of genus 9 ~ 2, which has the hyperbolic plane as universal covering rienmannian surface. It is known that the system of Fricke coordinates in Tg associates each surface to a fundamental of Voronoi-Dirichlet domain, given by convex polygon with 49 edges. We know that, with fixed genus, the density increases with the number of edges of the chosen Voronoi-Dirichlet domain. Thus it is naturallooking for polygons with a maximum number of edges associated to a given genus, which is always limited by 129 - 6.In this work, we determine Fricke coordinates in Tg which associates each surface to a Voronoi-Dirichlet domain with 49 + 2 and 129 - 6 edges. Furthermore, we determine and we program the algorithms for determination of the inscribed and circumscribed circles of a polygon (in surfaces of constant curvature). These algorithms, have com-plexity O (n4) , but when restricted to open neighbourhoods of a given polygon, have complexity O (n), best situation.The determination of the Voronoi-Dirichlet domain from the inscribed circles per-mits to define the packing of density directly on teichmüller spaces through a polyno-mials of system equations

ASSUNTO(S)

geometria hiperbolica grupos discretos (matematica) empacotamento e cobertura combinatoria espaços de reimann superficies de teichmuller

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