Geometric presentations of classical knot groups.
The article deals with bundles of linear algebra as a specifications of the case of smooth manifold. It allows to introduce on smooth manifold a metric by a natural way. The transfer of geometric structure arising in the linear spaces of associative algebras to a smooth manifold is also presented.
Let be a surface, let be a subsurface, and let be two positive integers. The inclusion of in gives rise to a homomorphism from the braid group with strings on to the braid group with strings on . We first determine necessary and sufficient conditions that this homomorphism is injective, and we characterize the commensurator, the normalizer and the centralizer of in . Then we calculate the commensurator, the normalizer and the centralizer of in for large surface braid...
Let be a knot in the -sphere , and a disk in meeting transversely in the interior. For non-triviality we assume that over all isotopies of in . Let () be a knot obtained from by twistings along the disk . If the original knot is unknotted in , we call a twisted knot. We describe for which pair and an integer , the twisted knot is a torus knot, a satellite knot or a hyperbolic knot.
À tout dessin d’enfant est associé un revêtement ramifié de la droite projective complexe , non ramifié en dehors de 0, 1 et l’infini. Cet article a pour but de décrire la structure algébrique de l’image réciproque de la droite projective réelle par ce revêtement, en termes de la combinatoire du dessin d’enfant. Sont rappelées en annexe les propriétés de la restriction de Weil et des dessins d’enfants utilisées.