A Relative cohomological invariant for group pairs.
A remark on subgroups of infinite index in Poincaré duality groups.
Algebraic properties of mapping class groups of surfaces
Almost-Bieberbach groups with prime order holonomy
The main issue of this paper is an attempt to find a decomposition theorem for infra-nilmanifolds in the same spirit as a result of A. Vasquez for flat Riemannian manifolds. That is: we look for infra-nilmanifolds with prime order holonomy which can be obtained as a fiber space with a non-trivial nilmanifold as fiber and an infra-nilmanifold as its base. In this perspective, we prove the following algebraic result: if E is an almost-Bieberbach group with prime order holonomy,...
An Abelian Quotient of the Mapping Class Group ...g.
An analytic interpretation of real dimension subgroups.
An infinite-dimensional torsion-free FP...group.
Artin-Gruppen und Coxeter-Gruppen.
Aspherical four-manifolds and the centres of two-knot groups.
Aspherical Group Presentations.
Automorphisms of free groups and their fixed points.
Automorphisms of surface mapping class groups. A recent theorem of N. Ivanov.
Caractéristiques d'euler et groupes fondamentaux des variétés de dimension 4.
Coherence of 3-manifold fundamental groups
Cohomological dimension and symmetric automorphisms of a free group.
Combins of Semidrect Products and 3-Manifold Groups.
Commensurations of the Johnson kernel.
Conformally non-sperical 2-complexes.
Conjugacy Relations in Subgroups of the Mapping Class Group and a Group-Theoretic Description of the Rochlin Invariant.
Co-rank and Betti number of a group
For a finitely generated group, we study the relations between its rank, the maximal rank of its free quotient, called co-rank (inner rank, cut number), and the maximal rank of its free abelian quotient, called the Betti number. We show that any combination of the group's rank, co-rank, and Betti number within obvious constraints is realized for some finitely presented group (for Betti number equal to rank, the group can be chosen torsion-free). In addition, we show that the Betti number is additive...