On -hyperelliptic involutions of Riemann surfaces.
On pq-hyperelliptic Riemann surfaces
A compact Riemann surface X of genus g > 1 is said to be p-hyperelliptic if X admits a conformal involution ϱ, called a p-hyperelliptic involution, for which X/ϱ is an orbifold of genus p. If in addition X admits a q-hypereliptic involution then we say that X is pq-hyperelliptic. We give a necessary and sufficient condition on p,q and g for existence of a pq-hyperelliptic Riemann surface of genus g. Moreover we give some conditions under which p- and q-hyperelliptic involutions of a pq-hyperelliptic...
On Spaces of Kleinian Groups
On supersoluble groups acting on Klein surfaces.
On the automorphism group of a toroidal hypermap
On the construction of non-congruence subgroups
On the Margulis constant for Kleinian groups. I.
On the number of subgroups of given index in the modular group.
On the representations of GL (2). II. ...-factors of the representations of GL(2) x GL(2).
On the subgroups of the Picard group.
Pairs of symmetries of Riemann surfaces.
Parabolic bundles, elliptic surfaces and SU (2)-representation spaces of genus zero Fuchsian groups.
Plane Motion Groups and Virtual Poincaré Duality of Dimension Two.
Poincaré duality groups of dimension two.
Power subgroups of Hecke groups .
Principal congruence link complements
In this paper we study principal congruence link complements in . It is known that there are only finitely many such link complements, and we make a start on enumerating them using a combination of theoretical methods and computer calculations with MAGMA.
Proper periods of normal N.E.C. subgroups with even index.
By a non-Euclidean crystallographic (N.E.C.) group we shall mean a discrete subgroup Γ of isometries of the non-Euclidean plane including those reverse orientation, reflections and glide-reflections.In [1] we computed the proper periods of normal N.E.C. subgroups of an N.E.C. group, when the index of the group with respect to the subgroup is odd. In this paper we shall compute the proper period of normal N.E.C. subgroups, when the index is even.The corresponding problem for Fuchsian groups, which...
Propriétés générales des substitutions à une variable et des fonctions qu'elles laissent invariables
-hyperelliptic compact nonorientable Klein surfaces without boundary.
Riemann and Klein surfaces with nodes viewed as quotients.
If G is a group of automorphisms that acts properly discontinuously on a Riemann or Klein surface X, then there exists a unique structure of Riemann or Klein surface on X/G such that the projection π: X → X/G is a morphism. The analogous result is not true when we deal with surfaces with nodes. In this paper we give a new definition of a group that acts properly discontinuously on a surface with nodes in order to obtain a similar theorem.