Corrigendum et addendum ad: “Minimal cell coverings of sphere bundles over spheres”
Covering homotopy 3-spheres.
Coverings defined by Weierstraß polynomials.
Coverings of S3 branched over iterated torus links.
Coverings of S3 branched over iterated torus links appear naturally and very often in Algebraic Geometry. The natural graph-manifold structure of the exterior of an iterated torus link induces a graph-structure in the branched covers. In this paper we give an algorithm to compute valued graphs representing a branched cover given the monodromy representation associated to the covering. The algorithm is completely mechanized in order to be programmed, and can also be used for finding representation...
Cyclic actions on - and -bundles over
Cyclic branched coverings and homology 3-spheres with large group actions
We show that, if the covering involution of a 3-manifold M occurring as the 2-fold branched covering of a knot in the 3-sphere is contained in a finite nonabelian simple group G of diffeomorphisms of M, then M is a homology 3-sphere and G isomorphic to the alternating or dodecahedral group 𝔸₅ ≅ PSL(2,5). An example of such a 3-manifold is the spherical Poincaré sphere. We construct hyperbolic analogues of the Poincaré sphere. We also give examples of hyperbolic ℤ₂-homology 3-spheres with PSL(2,q)-actions,...
Cyclic branched coverings of 2-bridge knots.
In this paper we study the connections between cyclic presentations of groups and the fundamental group of cyclic branched coverings of 2-bridge knots. Then we show that the topology of these manifolds (and knots) arises, in a natural way, from the algebraic properties of such presentations.
Cyclic branched coverings of knots and homology spheres.
We study cyclic coverings of S3 branched over a knot, and study conditions under which the covering is a homology sphere. We show that the sequence of orders of the first homology groups for a given knot is either periodic of tends to infinity with the order of the covering, a result recently obtained independently by Riley. From our computations it follows that, if surgery on a knot k with less than 10 crossings produces a manifold with cyclic fundamental group, then k is a torus knot.
Deformation of Maps to Branched Coverings in Dimension Three.
Description chirurgicale des revêtements triples simples de ramifiés le long d’un entrelacs
Nous présentons un algorithme permettant de convertir une présentation de variété de dimension 3 comme revêtement simple à trois feuillets de la sphère en une présentation de chirurgie.
Elements of finite order in the fundamental group of a branched cyclic covering.
Embeddings and imnmersions of branched covering spaces.
Estudio intrínseco de piezas Navier-hiperelásticas (Elastostática de piezas longitudinales conservativas).
Genera of Ramified Coverings.
Geometrically fibred two-knots.
Géométrie réelle des dessins d’enfant
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.
Heegaard and regular genus of 3-manifolds with boundary.
By means of branched coverings techniques, we prove that the Heegaard genus and the regular genus of an orientable 3-manifold with boundary coincide.
Heegaard Splittings and Branched Coverings of B3.
Hyperbolic knots and cyclic branched covers.
We collect several results on the determination of hyperbolic knots by means of their cyclic branched covers. We construct examples of knots having two common cyclic branched covers. Finally, we briefiy discuss the problem of determination of hyperbolic links.
Invariants of branched covering from the work of Serre and Mumford.