The determination of parabolic points in modular and extended modular groups by continued fractions.
The finite subgroups of maximal arithmetic kleinian groups
Given a maximal arithmetic Kleinian group , we compute its finite subgroups in terms of the arithmetic data associated to by Borel. This has applications to the study of arithmetic hyperbolic 3-manifolds.
The full automorphism group of the Kulkarni surface.
The full automorphism group of the Kulkarni surface is explicitly determined. It is employed to give three defining equations of the Kulkarni surface; each equation exhibits a symmetry of the surface as complex conjugation.
The full automorphism groups of hyperelliptic Riemann surfaces.
The geometry and spectrum of the one holed torus.
The mixed elliptically fixed point property for Kleinian groups.
The modular group action on real characters of a one-holed torus.
Theory of coverings in the study of Riemann surfaces
For a G-covering Y → Y/G = X induced by a properly discontinuous action of a group G on a topological space Y, there is a natural action of π(X,x) on the set F of points in Y with nontrivial stabilizers in G. We study the covering of X obtained from the universal covering of X and the left action of π(X,x) on F. We find a formula for the number of fixed points of an element g ∈ G which is a generalization of Macbeath's formula applied to an automorphism of a Riemann surface. We give a new method...
Torsion Free Subgroups of Fuchsian Groups and Tessalations of Surfaces.
Traces, lengths, axes and commensurability
The focus of this paper are questions related to how various geometric and analytical properties of hyperbolic 3-manifolds determine the commensurability class of such manifolds. The paper is for the large part a survey of recent work.
Triangle subgroups of Kleinian groups.
Two Generator Fuchsian Groups of Genus One.
Two-Generator Discrete Free Products.
Über die Heckeschen Gruppen G(...) II.
Über eine Klasse von arithmetischen definierbaren Normalteilern der Modulgruppe.
Über Erzeugende ebener diskontinuierlicher Gruppen.
Über explizite Präsentationen Hilbertscher Modulgruppen zu totalrellen Körpern der Klassenzahlen eins.
Über Tschebyscheff-Polynome, Nicht-Kongruenzuntergruppen der Modulgruppe und Fibonacci-Zahlen.
Über vollständige Automorphismengruppen und Gleichungen in der Modulgruppe
Ueber binäre Formen mit linearen Transformationen in sich selbst