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...
Corrigendum to: "Aspherical four-manifolds and the centres of two-knot groups".