Sur la topologie de certains espaces homogènes

  title={Sur la topologie de certains espaces homog{\`e}nes},
  author={Charles Ehresmann},

On the Contribution of Wu Wen-Tsün to Algebraic Topology

  • J. Brasselet
  • Mathematics
    Journal of Systems Science and Complexity
  • 2019
The aim of this article is to present the contribution of Wu Wen-Tsün to Algebraic Topology and more precisely to the theory of characteristic classes. Several papers provide complete and

On the Ehresmann cell structure for flag manifolds

The cell structure for flag manifolds, originally defined by Ehresmann, has certain deficiencies in the sense it does not allow for an exhaustive proof of the axioms in the definition of a

On the cell structure of flag manifolds

We here define a cell structure for real, complex and quaternionic flag manifolds in a unified way. Our method is geometric in nature and is inspired from a method due to Milnor and Stasheff, which

On Schubert’s Problem of Characteristics

The Schubert varieties on a flag manifold G/P give rise to a cell decomposition on G/P whose Kronecker duals, known as the Schubert classes on G/P, form an additive base of the integral cohomology of

On the Structure of the Bigrassmannian Permutation Poset

Let $\mathfrak{S}_n$ and $\mathfrak{B}_n$ denote the respective sets of ordinary and bigrassmannian permutations of order $n$, and let $(\mathfrak{S}_n,\le)$ denote the Bruhat ordering permutation

Invariant Principal Order Ideals under Foata's Transformation

A characterization of permutations of $\sigma$ such that ${\Lambda}_{\sigma}$ are invariant under $\Phi$, and the invariant principal order ideals with respect to the Bruhat order under Han's bijection.

Hodge Structure of a Complete Intersection of Quadrics in a Projective Space

Given a smooth projective variety V of dimension n, one may say that V has motivic dimension less than d+1 if the cohomology of V comes from varieties of dimensions less than d+1 in some geometric

Grothendieck polynomials via permutation patterns and chains in the Bruhat order

We give new formulas for Grothendieck polynomials of two types. One type expresses any specialization of a Grothendieck polynomial in at least two sets of variables as a linear combination of

Hook Interpolations

Schubert calculus and Intersection theory of Flag manifolds

Hilbert’s 15th problem called for a rigorous foundation of Schubert’s calculus, in which a long standing and challenging part is Schubert’s problem of characteristics. In the course of securing the