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Codimension 4 singularities on reflectionally symmetryc planar vector fields.

Freddy Dumortier, Santiago Ibáñez (1999)

Publicacions Matemàtiques

The paper deals with the topological classification of singularities of vector fields on the plane which are invariant under reflection with respect to a line. As it has been proved in previous papers, such a classification is necessary to determine the different topological types of singularities of vector fiels on R3 whose linear part is invariant under rotations. To get the classification we use normal form theory and the the blowing-up method.

Effective algebraic geometry and normal forms of reversible mappings.

Alain Jacquemard, Marco Antonio Teixeira (2002)

Revista Matemática Complutense

We present a new method to compute normal forms, applied to the germs of reversible mappings. We translate the classification problem of these germs to the theory of ideals in the space of the coefficients of their jets. Integral factorization coupled with Gröbner basis constructionjs the key factor that makes the process efficient. We also show that a language with typed objects like AXIOM is very convenient to solve these kinds of problems.

Geometry and representation of the singular symplectic forms

Wojciech Domitrz, Stanisław Janeczko, Zbigniew Pasternak-Winiarski (2003)

Banach Center Publications

In this paper we show to what extent the closed, singular 2-forms are represented, up to the smooth equivalence, by their restrictions to the corresponding singularity set. In the normalization procedure of the singularity set we find the sufficient conditions for the given closed 2-form to be a pullback of the classical Darboux form. We also find the classification list of simple singularities of the maximal isotropic submanifold-germs in the codimension one Martinet's singular symplectic structures....

Local reduction theorems and invariants for singular contact structures

Bronislaw Jakubczyk, Michail Zhitomirskii (2001)

Annales de l’institut Fourier

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

Local symplectic algebra of quasi-homogeneous curves

Wojciech Domitrz (2009)

Fundamenta Mathematicae

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...

On vanishing inflection points of plane curves

Mauricio Garay (2002)

Annales de l’institut Fourier

We study the local behaviour of inflection points of families of plane curves in the projective plane. We develop normal forms and versal deformation concepts for holomorphic function germs f : ( 2 , 0 ) ( , 0 ) which take into account the inflection points of the fibres of f . We give a classification of such function- germs which is a projective analog of Arnold’s A,D,E classification. We compute the versal deformation with respect to inflections of Morse function-germs.

Singularities of convex hulls as fronts of Legendre varieties

Ilia Bogaevski (1999)

Banach Center Publications

We describe singularities of the convex hull of a generic compact smooth hypersurface in four-dimensional affine space up to diffeomorphism. It turns out that the boundary of the convex hull is the front of a Legendre variety. Its singularities are classified up to contact diffeomorphism.

Symplectic classification of parametric complex plane curves

Goo Ishikawa, Stanisław Janeczko (2010)

Annales Polonici Mathematici

Based on the discovery that the δ-invariant is the symplectic codimension of a parametric plane curve singularity, we classify the simple and uni-modal singularities of parametric plane curves under symplectic equivalence. A new symplectic deformation theory of curve singularities is established, and the corresponding cyclic symplectic moduli spaces are reconstructed as canonical ambient spaces for the diffeomorphism moduli spaces which are no longer Hausdorff spaces.

The Quantum Birkhoff Normal Form and Spectral Asymptotics

San Vũ Ngọc (2006)

Journées Équations aux dérivées partielles

In this talk we explain a simple treatment of the quantum Birkhoff normal form for semiclassical pseudo-differential operators with smooth coefficients. The normal form is applied to describe the discrete spectrum in a generalised non-degenerate potential well, yielding uniform estimates in the energy E . This permits a detailed study of the spectrum in various asymptotic regions of the parameters ( E , ) , and gives improvements and new proofs for many of the results in the field. In the completely resonant...

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