Dans cet article, on donne une démonstration explicite du théorème de M. Sebastiani, sur la liberté du $\mathbf{C}\left\{p\right\}$ module $G={\Omega }^n/dP\wedge d{\Omega }^{n-2}$ associé à un germe à singularité isolée, lorsque $P$ est quasi homogène.Il se distingue, dans ce cas, une base et les fonctions composantes d’un élément de $G$ sont produites par un algorithme dont on prouve la convergence avec le théorème des voisinages privilégiés de B. Malgrange.

A differential 1-form on a $(2k+1)$-dimensional manifolds $M$ defines a singular contact structure if the set $S$ of points where the contact condition is not satisfied, $S=\{p\in M:(\omega \wedge {\left(d\omega \right)}^k\left(p\right)=0\}$, is nowhere dense in $M$. Then $S$ is a hypersurface with singularities and the restriction of $\omega$ to $S$ can be defined. Our first theorem states that in the holomorphic, real-analytic, and smooth categories the germ of Pfaffian equation $\left(\omega \right)$ generated by $\omega$ is determined, up to a diffeomorphism, by its restriction to $S$, if we eliminate certain degenerated singularities...

We study the local symplectic algebra of parameterized curves introduced by V. I. Arnold. We use the method of algebraic restrictions to classify symplectic singularities of quasi-homogeneous curves. We prove that the space of algebraic restrictions of closed 2-forms to the germ of a 𝕂-analytic curve is a finite-dimensional vector space. We also show that the action of local diffeomorphisms preserving the quasi-homogeneous curve on this vector space is determined by the infinitesimal action of...

Let $G:{ℂ}^n\times {ℂ}^r\to ℂ$ be a holomorphic family of functions. If $\Lambda \subset {ℂ}^n\times {ℂ}^r$, ${\pi }_r:{ℂ}^n\times {ℂ}^r\to {ℂ}^r$ is an analytic variety then   $Q_{\Lambda }\left(G\right)=(x,u)\in {ℂ}^n\times {ℂ}^r:G(·,u)hasacriticalpointin\Lambda \cap {\pi }_r^{-1}\left(u\right)$is a natural generalization of the bifurcation variety of G. We investigate the local structure of $Q_{\Lambda }\left(G\right)$ for locally trivial deformations of $\Lambda ₀={\pi }_r^{-1}\left(0\right)$. In particular, we construct an algorithm for determining logarithmic stratifications provided G is versal.