Radical relations in unitary, symplectic, and orthogonal groups.
Radix redux: Normal subgroups of symplectic groups.
Ramanujan-Identitäten zur Reziproken der Jacobischen Funktion .. .
Real Strict Localizations.
Reduction theory using semistability.
Reduction theory using semistability, II.
Representations of p-groups at characteristic p l
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.