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Claude Viterbo

Publications and source records attributed to Claude Viterbo.

At least 19 recordsLinked to original sources
arXiv2026

Density of fibers for the filtered Fukaya category of $T^*N$

We answer a question of Biran and Cornea about the density of iterated cones of fibers in the Fukaya category of a cotangent bundle. We prove that indeed if we take a dense set of basepoints, the iterated cones of the cotangent fibres are dense in the Filtered Fukaya category. In an appendix we prove that the space of exact Lagrangians in a symplectic manifold is never totally bounded for the spectral distance (unless it is empty). This was implicit in \cite{MCA-VH-CV} for $n=1$ and proved for cotangent bundles of negatively curved manifolds in \cite{A-B-C}.

math.SG↗
arXiv2024

Regular Lagrangians are smooth Lagrangians

We prove that for any element in the $\gamma$-completion of the space of smooth compact exact Lagrangian submanifolds of a cotangent bundle, if its $\gamma$-support is a smooth Lagrangian submanifold, then the element itself is a smooth Lagrangian. We also prove that if the $\gamma$-support of an element in the completion is compact, then it is connected.

math.SG↗
arXiv2024

Higher Dimensional Birkhoff attractors (with an appendix by Maxime Zavidovique)

We extend to higher dimensions the notion of Birkhoff attractor of a dissipative map. We prove that this notion coincides with the classical Birkhoff attractor. We prove that for the dissipative system associated to the discounted Hamilton-Jacobi equation the graph of a solution is contained in the Birkhoff attractor. We also study what happens when we perturb a Hamiltonian system to make it dissipative and let the perturbation go to zero. The paper contains two important results on $\gamma$-supports and elements of the $\gamma$-completion of the space of exact Lagrangians. Firstly the $\gamma$-support of a Lagrangian in a cotangent bundle carries the cohomology of the base and secondly given an exact Lagrangian $L$, any Floer theoretic equivalent Lagrangian is the $\gamma$-limit of Hamiltonian images of $L$. The appendix provides instructive counter-examples.

math.SG↗
arXiv2023

The $γ$-support as a micro-support

We prove that for any element $L$ in the completion of the space of smooth compact exact Lagrangian submanifolds of a cotangent bundle equipped with the spectral distance, the $γ$-support of $L$ coincides with the reduced micro-support of its sheaf quantization. As an application, we give a characterization of the Vichery subdifferential in terms of $γ$-support.

math.SG↗
arXiv2023

The singular support of sheaves is $γ$-coisotropic

We prove that the singular support of an element in the derived category of sheaves is $γ$-coisotropic, a notion defined in [Vit22]. We prove that this implies that it is involutive in the sense of Kashiwara-Schapira, but being $γ$-coisotropic has the advantage to be invariant by symplectic homeomorphisms (while involutivity is only invariant by $C^1$ diffeomorphisms) and we give an example of an involutive set that is not $γ$-coisotropic. Along the way we prove a number of results relating the singular support and the spectral norm $γ$ and raise a number of new questions.

math.SG↗
arXiv2022

Symplectic Homogenization

Let $H(q,p)$ be a Hamiltonian on $T^*T^n$. We show that the sequence $H_{k}(q,p)=H(kq,p)$ converges for the $γ$ topology defined by the author, to $\bar{H}(p)$. This is extended to the case where only some of the variables are homogenized, that is the sequence $H(kx,y,q,p)$ where the limit is of the type ${\bar H}(y,q,p)$ and thus yields an "effective Hamiltonian". We give here the proof of the convergence, and the first properties of the homogenization operator, and give some immediate consequences for solutions of Hamilton-Jacobi equations, construction of quasi-states, etc. We also prove that the function $\bar H$ coincides with Mather's $α$ function which gives a new proof of its symplectic invariance proved by P. Bernard. A previous version of this paper relied on the former "On the capacity of Lagrangians in $T^*T^n$ which has been withdrawn. The present version of Symplectic Homogenization does not rely on it anymore.

math.SG↗
arXiv2022

On the supports in the Humili\`ere completion and $\gamma$-coisotropic sets

The symplectic spectral metric on the set of Lagrangian submanifolds or Hamiltonian maps can be used to define a completion of these spaces. For an element of such a completion, we define its $\gamma$-support. We also define the notion of $\gamma$-coisotropic set, and prove that a $\gamma$-support must be $\gamma$-coisotropic toghether with many properties of the $\gamma$-support and $\gamma$-coisotropic sets. We give examples of Lagrangians in the completion having large $\gamma$-support and we study those (called "regular Lagrangians") having small $\gamma$-support. We compare the notion of $\gamma$-coisotropy with other notions of isotropy.

math.SG↗
arXiv2022

Inverse reduction inequalities for spectral numbers and applications

Our main result is the proof of an inequality between the spectral numbers of a Lagrangian and the spectral numbers of its reductions, in the opposite direction to the classical inequality (see e.g [Vit92]). This has applications to the "Geometrically bounded Lagrangians are spectrally bounded" conjecture from [Vit08], to the structure of elements in the $γ$-completion of the set of exact Lagrangians. We also investigate the local path-connectedness of the set of Hamiltonian diffeomorphisms with the spectral metric.

math.SG↗
arXiv2021

Stochastic homogenization for variational solutions of Hamilton-Jacobi equations

Let $(\Omega, \mu)$ be a probability space endowed with an ergodic action, $\tau$ of $( {\mathbb R} ^n, +)$. Let $H(x,p; \omega)=H_\omega(x,p)$ be a smooth Hamiltonian on $T^* {\mathbb R} ^n$ parametrized by $\omega\in \Omega$ and such that $ H(a+x,p;\tau_a\omega)=H(x,p;\omega)$. We consider for an initial condition $f\in C^0 ( {\mathbb R}^n)$, the family of variational solutions of the stochastic Hamilton-Jacobi equations $$\left\{ \begin{aligned} \frac{\partial u^{ \varepsilon }}{\partial t}(t,x;\omega)+H\left (\frac{x}{ \varepsilon } , \frac{\partial u^\varepsilon }{\partial x}(t,x;\omega);\omega \right )=0 &\\ u^\varepsilon (0,x;\omega)=f(x)& \end{aligned} \right .$$ Under some coercivity assumptions on $p$ -- but without any convexity assumption -- we prove that for a.e. $\omega \in \Omega$ we have $C^0-\lim u^{\varepsilon}(t,x;\omega)=v(t,x)$ where $v$ is the variational solution of the homogenized equation $$\left\{ \begin{aligned} \frac{\partial v}{\partial t}(x)+{\overline H}\left (\frac{\partial v }{\partial x}(x) \right )=0 &\\ v (0,x)=f(x)& \end{aligned} \right.$$

math.AP↗
arXiv2019

Sheaf Quantization of Lagrangians and Floer cohomology

Given an exact Lagrangian submanifold $L$ in $T^*N$, we want to construct a complex of sheaves in the derived category of sheaves on $N\times {\mathbb R} $, such that its singular support, $SS({\mathcal F}^\bullet_L)$, is equal to $\widehat L$, the cone constructed over $L$. Its existence was stated in \cite{Viterbo-ISTST} in 2011, with a sketch of proof, which however contained a gap (fixed here by the rectification). A complete proof was shortly after provided by Guillermou (\cite{Guillermou}) by a completely different method, in particular Guillermou's method does not use Floer theory. The proof provided here is, as originally planned, based on Floer homology. Besides the construction of the complex of sheaves, we prove that the filtered versions of sheaf cohomology of the quantization and of Floer cohomology coincide, that is $FH^*(N\times ]-\infty, λ[, {\mathcal F}^\bullet_L)\simeq FH^*(L;0_N;λ)$, and so do their product structures.

math.SG↗
arXiv2018

Barcodes and area-preserving homeomorphisms

In this paper we use the theory of barcodes as a new tool for studying dynamics of area-preserving homeomorphisms. We will show that the barcode of a Hamiltonian diffeomorphism of a surface depends continuously on the diffeomorphism, and furthermore define barcodes for Hamiltonian homeomorphisms. Our main dynamical application concerns the notion of {\it weak conjugacy}, an equivalence relation which arises naturally in connection to $C^0$ continuous conjugacy invariants of Hamiltonian homeomorphisms. We show that for a large class of Hamiltonian homeomorphisms with a finite number of fixed points, the number of fixed points, counted with multiplicity, is a weak conjugacy invariant. The proof relies, in addition to the theory of barcodes, on techniques from surface dynamics such as Le Calvez's theory of transverse foliations. In our exposition of barcodes and persistence modules, we present a proof of the Isometry Theorem which incorporates Barannikov's theory of simple Morse complexes.

math.SG↗
arXiv2018

Non-convex Mather's theory and the Conley conjecture on the cotangent bundle of the torus

The aim of this paper is to use the methods and results of symplectic homogenization (see [V4]) to prove existence of periodic orbits and invariant measures with rotation number depending on the differential of the Homogenized Hamiltonian. We also prove the Conley conjecture on the cotangent bundle of the torus. Both proofs rely on Symplectic Homogenization and a refinement of it.

math.DS↗
arXiv2010

Action minimizing properties and distances on the group of Hamiltonian diffeomorphisms

In this article we prove that for a smooth fiberwise convex Hamiltonian, the asymptotic Hofer distance from the identity gives a strict upper bound to the value at 0 of Mather's $β$ function, thus providing a negative answer to a question asked by K. Siburg in \cite{Siburg1998}. However, we show that equality holds if one considers the asymptotic distance defined in \cite{Viterbo1992}.

math.SG↗
arXiv2009

On the topology of fillings of contact manifolds and applications

The aim of this paper is to address the following question: given a contact manifold $(Σ, ξ)$, what can be said about the aspherical symplectic manifolds $(W, ω)$ bounded by $(Σ, ξ)$ ? We first extend a theorem of Eliashberg, Floer and McDuff to prove that under suitable assumptions the map from $H_{*}(Σ)$ to $H_{*}(W)$ induced by inclusion is surjective. We then apply this method in the case of contact manifolds having a contact embedding in $ {\mathbb R}^{2n}$ or in a subcritical Stein manifold. We prove in many cases that the homology of the fillings is uniquely determined. Finally we use more recent methods of symplectic topology to prove that, if a contact hypersurface has a Stein subcritical filling, then all its weakly subcritical fillings have the same homology. A number of applications are given, from obstructions to the existence of Lagrangian or contact embeddings, to the exotic nature of some contact structures.

math.SG↗
arXiv2007

Commuting Hamiltonians and multi-time Hamilton-Jacobi equations

We prove that if a sequence of pairs of smooth commuting Hamiltonians converge in the $C^0$ topology to a pair of smooth Hamiltonians, these commute. This allows us define the notion of commuting continuous Hamiltonians. As an application we extend some results of Barles and Tourin on multi-time Hamilton-Jacobi equations to a more general setting.

math.SG↗