On Thom-Whitney Stratification Theory.
Polymersions of a disk with critical points on the boundary.
Positivity of Schur function expansions of Thom polynomials
Combining the approach to Thom polynomials via classifying spaces of singularities with the Fulton-Lazarsfeld theory of cone classes and positive polynomials for ample vector bundles, we show that the coefficients of the Schur function expansions of the Thom polynomials of stable singularities are nonnegative with positive sum.
Positivity of Thom polynomials II: the Lagrange singularities
We study Thom polynomials associated with Lagrange singularities. We expand them in the basis of Q̃-functions. This basis plays a key role in the Schubert calculus of isotropic Grassmannians. We prove that the Q̃-function expansions of the Thom polynomials of Lagrange singularities always have nonnegative coefficients. This is an analog of a result on the Thom polynomials of mapping singularities and Schur S-functions, established formerly by the last two authors.
Quadratische Formen und Monodromiegruppen von Singularitäten.
Quelques calculs en cobordisme lagrangien
Nous considérons les groupes de cobordisme (définis par Arnold) d’immersions lagrangiennes exactes de variétés compactes dans . Grâce au théorème de Gromov-Lees, leur calcul est celui des groupes d’homotopie de spectres de Thom construits sur les espaces (cas non-orienté, le calcul est alors dû à Smith et Stong) et (cas orienté, groupes dont nous calculons la “partie paire”, et sur la “partie impaire” desquels nous donnons des informations). Nous calculons aussi les images de ces groupes dans...
Real Analytic Germs and Theri Varieties at Isolated Singularities.
Real singularities and open-book decompositions of the 3-sphere
Remarks on the symmetries of planar fronts.
A front is the projection on the plane of a Legendrian immersion of a circle in the space of the contact elements of that plane. I analyze the symmetries of a generic front with respect to the group generated by the involutions reversing the orientation of the plane, the orientation of the preimage circle and the coorientation of the contact plane.
Rigidity and gluing for Morse and Novikov complexes
We obtain rigidity and gluing results for the Morse complex of a real-valued Morse function as well as for the Novikov complex of a circle-valued Morse function. A rigidity result is also proved for the Floer complex of a hamiltonian defined on a closed symplectic manifold with . The rigidity results for these complexes show that the complex of a fixed generic function/hamiltonian is a retract of the Morse (respectively Novikov or Floer) complex of any other sufficiently close generic function/hamiltonian....
Schur and Schubert polynomials as Thom polynomials-cohomology of moduli spaces
The theory of Schur and Schubert polynomials is revisited in this paper from the point of view of generalized Thom polynomials. When we apply a general method to compute Thom polynomials for this case we obtain a new definition for (double versions of) Schur and Schubert polynomials: they will be solutions of interpolation problems.
Secondary characteristic classes for the isotropic Grassmannian
Simple framed curve singularities
We obtain a complete list of simple framed curve singularities in ℂ² and ℂ³ up to the framed equivalence. We also find all the adjacencies between simple framed curves.
Singular fibers of stable maps and signatures of 4-manifolds.
Singular open book structures from real mappings
We define open book structures with singular bindings. Starting with an extension of Milnor’s results on local fibrations for germs with nonisolated singularity, we find classes of genuine real analytic mappings which yield such open book structures.
Singularité générique des applications différentiables de la 2-sphère dans une 3-variété différentiable
Dans cet article nous étudions les singularités des applications différentiables de la deux sphère dans une trois variété avec les méthodes de transversalité et nous utilisons les résultats obtenus pour reprendre dans le cas différentiable, les démonstrations de Papakyriakopoulos et de Whitehead du théorème de la sphère.
Singularities and duality in the flat geometry of submanifolds of Euclidean spaces.
Singularities II: Automorphisms of Forms.
Singularities in contact geometry
In the first half of the paper, we consider singularities of infinitesimal contact transformations and first order partial differential equations, the main results being related to the classical Sternberg-Chen theorem for hyperbolic germs of vector fields. The second half explains how to construct global generating phase functions for solutions of Hamilton-Jacobi equations and see what their singularities look like.
Singularities in drawings of singular surfaces
When drawing regular surfaces, one creates a concrete and visual example of a projection between two spaces of dimension 2. The singularities of the projection define the apparent contour of the surface. As a result there are two types of generic singularities: fold and cusp (Whitney singularities). The case of singular surfaces is much more complex. A priori, it is expected that new singularities may appear, resulting from the "interaction" between the singularities of the surface and the singularities...