Poincaré submersions.
Nous montrons que le sous-groupe des points fixes d’un automorphisme d’un groupe hyperbolique au sens de M. Gromov est de type fini.
Let L = X U Y be an oriented 2-component link in S3. In this paper we will define two different types of polynomials which are ambient isotopic invariants of L. One is associated with a cyclic cover branched along one of their components, an the other is associated with a metabelian cover of L. This invariants are defined for any link unless the linking number lk(X,Y), is ±1.
The Homflypt and Kauffman skein modules of the projective space are computed. Both are free and generated by some infinite set of links. This set may be chosen to be {Lₙ: n ∈ ℕ ∪ {0}}, where Lₙ is an arbitrary link consisting of n projective lines for n > 0, and L₀ is an affine unknot.
Si dimostra che per le varietà a struttura quaternionale generalizzata integrabile, le classi di Pontrjagin sono generate dalle classi di Pontrjagin del fibrato vettoriale fondamentale.