Strongly homotopically stabile points
Subspace and addition theorems for extension and cohomological dimensions. A problem of Kuzminov
Suites Fσ -absorbantes en théorie de la dimension
Suites spectrales de Hochschild-Serre à coefficients dans un espace semi-normé.
In this paper, we prove the existence of the theory of spectral sequences in the category of real semi normed spaces. Using this theory, we associate to any extension of discrete groups the Hochschild-Serre spectral sequence in bounded cohomology with coefficients. In addition, we give the explicit expression of the first and the second term of this spectral sequence without further hypothesis.
Superextensions and Lefschetz fixed point structures
Sur la catégorie de Lusternik-Schnirelmann des algèbres de cochaînes
Nous introduisons une nouvelle définition d’un invariant bicat pour une algèbre de cochaînes connexe et 1-connexe, de type fini sur un corps de caractéristique quelconque, et nous montrons d’une part, qu’il coïncide avec l’invariant cat introduit par S. Halperin et J.-M. Lemaire et d’autre part, qu’il est invariant par extension de corps et qu’il vérifie la conjecture de Ganéa.
Sur la dualité de Poincaré.
Sur les invariants d'homotopie rationnelle liés à la L.S. catégorie.
Symmetrie Products of ANR's.
Tetrahedra on deformed spheres and integral group cohomology.
The ℤ₂-cohomology cup-length of real flag manifolds
Using fiberings, we determine the cup-length and the Lyusternik-Shnirel’man category for some infinite families of real flag manifolds , q ≥ 3. We also give, or describe ways to obtain, interesting estimates for the cup-length of any , q ≥ 3. To present another approach (combining well with the “method of fiberings”), we generalize to the real flag manifolds Stong’s approach used for calculations in the ℤ₂-cohomology algebra of the Grassmann manifolds.
The Anosov theorem for infranilmanifolds with an odd-order Abelian holonomy group.
The asymptotic dimension of the first Grigorchuk group is infinity.
We describe a sufficient condition for a finitely generated group to have infinite asymptotic dimension. As an application, we conclude that the first Grigorchuk group has infinite asymptotic dimension.
The boundary-Wecken classification of surfaces.
The Brouwer Fixed Point Theorem for Some Set Mappings
For some classes of closed subsets of the disc ₙ ⊂ ℝⁿ we prove that every Hausdorff-continuous mapping f: X → X has a fixed point A ∈ X in the sense that the intersection A ∩ f(A) is nonempty.
The Brouwer-Jordan theorem
The closure of a model category
The cohomology algebras of orientable Seifert manifolds and applications to Lusternik-Schnirelmann category
This note gives a complete description of the cohomology algebra of any orientable Seifert manifold with ℤ/p coefficients, for an arbitrary prime p. As an application, the existence of a degree one map from an orientable Seifert manifold onto a lens space is completely determined. A second application shows that the Lusternik-Schnirelmann category for a large class of Seifert manifolds is equal to 3, which in turn is used to verify the Ganea conjecture for these Seifert manifolds.
The coincidence index for fundamentally contractible multivalued maps with nonconvex values
We study a coincidence problem of the form A(x) ∈ ϕ (x), where A is a linear Fredholm operator with nonnegative index between Banach spaces and ϕ is a multivalued A-fundamentally contractible map (in particular, it is not necessarily compact). The main tool is a coincidence index, which becomes the well known Leray-Schauder fixed point index when A=id and ϕ is a compact singlevalued map. An application to boundary value problems for differential equations in Banach spaces is given.
The coincidence Nielsen number for maps into real projective spaces
We give an algorithm to compute the coincidence Nielsen number N(f,g), introduced in [DJ], for pairs of maps into real projective spaces.