arXiv subjects

Olivier Thom

Publications and source records attributed to Olivier Thom.

9 recordsLinked to original sources

arXiv2026

Irrational series I Laplace transform in a neighborhood of $-\infty$

Discrete sums of exponentials $g(w) = \sum a_β \mathrm{e}^{βw}$ with positive exponents may converge not normally in neighborhoods $H$ of $-\infty$ which do not contain half-planes. In order to obtain a decomposition of a holomorphic function $g$ in $H$ as a sum of exponentials we study the Laplace transform in general neighborhoods of $-\infty$. We adress questions such as continuity of Laplace and inverse Laplace transformations, continuity for the operation of taking partial sums, and resummation formulas.

math.CV↗

arXiv2026

Irrational series II Summation by packages

Discrete sums of exponentials $g(w) = \sum a_β \mathrm{e}^{βw}$ with positive exponents may converge not normally in neighborhoods $H$ of $-\infty$ which do not contain half-planes. We study different notions of convergence for these series and in particular the intuitive notion of summation by packages. Indeed, joining in packages the terms in the sum $g(w)$ whose exponents are close together, and summing first inside each package may result in massive cancellations. We show that discrete sums $g(w)$ which are bounded in what we call logarithmic neighborhoods can always be summated by packages.

math.CV↗

arXiv2021

About $\mathcal{C}^\infty$ foliations by holomorphic curves on complex surfaces

We study those real $\mathcal{C}^\infty$ foliations in complex surfaces whose leaves are holomorphic curves. The main motivation is to try and understand these foliations in neighborhoods of curves: can we expect the space of foliations in a fixed neighborhood to be infinite-dimensional, or are there some contexts under which every such foliation is holomorphic? We give some restrictions and study in more details the geometry of foliations whose leaves belong to a holomorphic family of holomorphic curves. In particular, we classify all real-analytic foliations on neighborhoods of curves which are locally diffeomorphic to foliations by lines, under some non-degeneracy hypothesis.

math.CV↗

arXiv2021

Dualité complexe entre sous-variétés réelles dans $\mathbb{P}^2(\mathbb{C})$

We introduce a notion of semi-legendrian real submanifold in a complex manifold of dimension 3 and prove that real submanifolds of $\mathbb{C}^2$ can be uniquely lifted to $\mathbb{C}^3$. Then we deduce a complex duality between real submanifolds of $\mathbb{P}^2(\mathbb{C})$.

math.GT↗

arXiv2020

On the formal principle for curves on projective surfaces

We prove that the formal completion of a complex projective surface along a rigid smooth curve with trivial normal bundle determines the birational equivalence class of the surface.

math.AG↗

arXiv2018

Décomposition en éléments simples des formes méromorphes formelles fermées

We show that any closed formal meromorphic 1-form admits a "partial fraction decomposition", which allows us in particular to define a notion of residue for closed formal meromorphic forms which extends the notion defined for usual forms.

math.CV↗

arXiv2018

Formal classication of two-dimensional neighborhoods of genus g $\ge$ 2 curves with trivial normal bundle

In this paper we study the formal classication of two-dimensional neighborhoods of genus g $\ge$ 2 curves with trivial normal bundle. We first construct formal foliations on such neighborhoods with holonomy vanishing along many loops, then give the formal/analytic classication of neighborhoods equipped with two foliations, and finally put this together to obtain a description of the space of neighborhoods up to formal equivalence.

math.AG↗

arXiv2018

Two dimensional neighborhoods of elliptic curves: formal classification and foliations

We classify two dimensional neighborhoods of an elliptic curve C with torsion normal bundle, up to formal equivalence. The proof makes use of the existence of a pair (indeed a pencil) of formal foliations having C as a common leaf, and the fact that neighborhoods are completely determined by the holonomy of such a pair. We also discussanalytic equivalence and show, for each formal model, that the corresponding moduli space is infinite dimensional.

math.CA↗

arXiv2017

Pairs of Morse functions

The goal of this paper is to classify pairs of Morse functions in general position modulo the action of different groups.In particular, we obtain the classification of generic pairs of Morse functions, with or without target diffeomorphisms, and that of quotients of Morse functions.We will also present a lemma which gives a sufficient condition for two pairs of functions to be conjugated.

math.CA↗