Holonomy groups of five dimensional Bieberbach groups.
Homeotopy groups of punctured spheres with holes
Homological stability for automorphism groups of free groups.
Homology cylinders and the acyclic closure of a free group.
Homomorphic extensions of Johnson homomorphisms via Fox calculus
Using Fox differential calculus, for any positive integer , we construct a map on the mapping class group of a surface of genus with one boundary component, such that, when restricted to an appropriate subgroup, it coincides with the Johnson-Morita homomorphism. This allows us to construct very easily a homomorphic extension to of the second and third Johnson-Morita homomorphisms.
Homotopy dimension and simple cohomological dimension of spaces.
Homotopy invariants of links.
Immersed and virtually embedded -injective surfaces in graph manifolds.
Incidence algebras and algebraic fundamental group.
Incompressibilité des feuilles de germes de feuilletages holomorphes singuliers
Nous considérons un germe de feuilletage holomorphe singulier non-dicritique défini sur une boule fermée , satisfaisant des hypothèses génériques, de courbe de séparatrice . Nous démontrons l’existence d’un voisinage ouvert de dans tel que, pour toute feuille de , l’inclusion naturelle induit un monomorphisme au niveau du groupe fondamental. Pour cela, nous introduisons la notion géométrique de « connexité feuilletée » avec laquelle nous réinterprétons la notion d’incompressibilité....
Instability of the eikonal equation and shape from shading
In the shape from shading problem of computer vision one attempts to recover the three-dimensional shape of an object or landscape from the shading on a single image. Under the assumptions that the surface is dusty, distant, and illuminated only from above, the problem reduces to that of solving the eikonal equation |Du|=f on a domain in . Despite various existence and uniqueness theorems for smooth solutions, we show that this problem is unstable, which is catastrophic for general numerical algorithms. ...
Isoperimetric inequalities and the homology of groups.
k-Invariants of knotted 2-spheres.
Knot manifolds with isomorphic spines
We study the relation between the concept of spine and the representation of orientable bordered 3-manifolds by Heegaard diagrams. As a consequence, we show that composing invertible non-amphicheiral knots yields examples of topologically different knot manifolds with isomorphic spines. These results are related to some questions listed in [9], [11] and recover the main theorem of [10] as a corollary. Finally, an application concerning knot manifolds of composite knots with h prime factors completes...
Le théorème de Van Kampen
L'image d'un groupe dans un groupe hyperbolique.
Link concordance and algebraic closure, II.
Localization of group rings and applications to 2-complexes.
Manifolds of even dimension with amenable fundamental group.
Manifolds with a given homology and fundamental gorup.