Nets associated with the elementary nets.
Noncongruence subgroups of the Hecke groups G (...).
Non-existence de certains polygones généralisés, I.
Non-existence de certains polygones généralisés. II.
Non-free two-generator subgroups of SL2(Q).
The question of whether two parabolic elements A, B of SL2(C) are a free basis for the group they generate is considered. Some known results are generalized, using the parameter τ = tr(AB) - 2. If τ = a/b ∈ Q, |τ| < 4, and |a| ≤ 16, then the group is not free. If the subgroup generated by b in Z / aZ has a set of representatives, each of which divides one of b ± 1, then the subgroup of SL2(C) will not be free.
Non-maximal cyclic group actions on compact Riemann surfaces.
We say that a finite group G of automorphisms of a Riemann surface X is non-maximal in genus g if (i) G acts as a group of automorphisms of some compact Riemann surface Xg of genus g and (ii), for all such surfaces Xg , |Aut Xg| > |G|. In this paper we investigate the case where G is a cyclic group Cn of order n. If Cn acts on only finitely many surfaces of genus g, then we completely solve the problem of finding all such pairs (n,g).
Non-minimal modular symbols for GL(n).
Normal structure of the adjoint group in the radical rings .
Normal subgroups of classical groups over Banach algebras.
Normal Subgroups of N.E.C. Groups.
Normalizers of Modular Groups.
Normalteiler ganzzahliger Spingruppen.
Normalteiler und Faktorstrukturen geschlitzter Inzidenzgruppen.
Note über das Geschlecht gewisser arithmetischer Gruppen.
Notiz über die Discontinuität gewisser Collineationsgruppen