Über Erweiterungen von Z und Z2 * Z2 durch nichteuklidische kristallographische Gruppen.
Über Gruppen von Homöomorphismen Seifertscher Faserräume und flacher Manigfaltigkeiten.
Über Homöomorphismen n-dimensionaler Henkelkörper und endliche Erweiterungen von Schottky-Gruppen.
Über offene Abbildungen auf die 3-Sphäre.
Ueber die Thatsachen, die der Geometrie zum Grunde liegen.
Ueber einen zu einer unendlichen Punktmenge gehörigen Grenzwerth
Umbilical characteristic number of Lagrangian mappings of 3-dimensional pseudooptical manifolds
As shown by V. Vassilyev [V], singularities of arbitrary Lagrangian mappings of three-folds form no integral characteristic class. We show, nevertheless, that in the pseudooptical case the number of singularities counted with proper signs forms an invariant. We give a topological interpretation of this invariant, and its applications. The results of the paper may be considered as a 3-dimensional generalization of the results due to V. I. Arnold [A].
Un algorithme pour calculer l'invariant de Walker
Un contre-exemple à la conjecture de Seifert
Un nouvel invariant pour les sphères d'homologie de dimension trois
Una caracterización topológica de las involuciones en superficies de Klein.
Une obstruction pour scinder une équivalence d’homotopie en dimension
Unified quantum invariants and their refinements for homology 3-spheres with 2-torsion
For every rational homology 3-sphere with H₁(M,ℤ) = (ℤ/2ℤ)ⁿ we construct a unified invariant (which takes values in a certain cyclotomic completion of a polynomial ring) such that the evaluation of this invariant at any odd root of unity provides the SO(3) Witten-Reshetikhin-Turaev invariant at this root, and at any even root of unity the SU(2) quantum invariant. Moreover, this unified invariant splits into a sum of the refined unified invariants dominating spin and cohomological refinements of...
Uniform sequences of -mappings
Uniformisation en dimension trois
Uniqueness of the embedding of a 2-complex into a 3-manifold.
Univalent mappings of the plane into itself
Universal manifold pairings and positivity.
Universal meager -sets in locally compact manifolds
In each manifold modeled on a finite or infinite dimensional cube , , we construct a meager -subset which is universal meager in the sense that for each meager subset there is a homeomorphism such that . We also prove that any two universal meager -sets in are ambiently homeomorphic.
Universal tessellations.
All maps of type (m,n) are covered by a universal map M(m,n) which lies on one of the three simply connected Riemann surfaces; in fact M(m,n) covers all maps of type (r,s) where r|m and s|n. In this paper we construct a tessellation M which is universal for all maps on all surfaces. We also consider the tessellation M(8,3) which covers all triangular maps. This coincides with the well-known Farey tessellation and we find many connections between M(8,3) and M.