BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Département de mathématiques et applications - ECPv6.2.2//NONSGML v1.0//EN CALSCALE:GREGORIAN METHOD:PUBLISH X-WR-CALNAME:Département de mathématiques et applications X-ORIGINAL-URL:https://www.math.ens.psl.eu X-WR-CALDESC:évènements pour Département de mathématiques et applications REFRESH-INTERVAL;VALUE=DURATION:PT1H X-Robots-Tag:noindex X-PUBLISHED-TTL:PT1H BEGIN:VTIMEZONE TZID:Europe/Paris BEGIN:DAYLIGHT TZOFFSETFROM:+0100 TZOFFSETTO:+0200 TZNAME:CEST DTSTART:20250330T010000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET DTSTART:20251026T010000 END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20250108T104500 DTEND;TZID=Europe/Paris:20250108T114500 DTSTAMP:20260425T164717 CREATED:20241126T135515Z LAST-MODIFIED:20250104T094906Z UID:18700-1736333100-1736336700@www.math.ens.psl.eu SUMMARY:Sharp constants in Fourier restriction inequalities #1 DESCRIPTION:The Fourier restriction inequalities originate from the work of Stein\, Tomas\, Strichartz and Sigal in the 1970s\, and imposed themselves as a cornerstone of modern harmonic analysis. In these three talks we will present the state of the art for the problem of determining these inequalities in sharp form\, that is\, with best possible constants and knowledge of the functions which attain them. We will explore a selection of recent results with detailed proofs. URL:https://www.math.ens.psl.eu/evenement/cours-de-giuseppe-negro-n1/ LOCATION:DMA – Salle R3\, 45 rue d'Ulm\, Paris\, 75005\, France CATEGORIES:Séminaire interne de l'équipe d'analyse END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20250115T104500 DTEND;TZID=Europe/Paris:20250115T114500 DTSTAMP:20260425T164717 CREATED:20241126T135634Z LAST-MODIFIED:20250104T094918Z UID:18705-1736937900-1736941500@www.math.ens.psl.eu SUMMARY:Sharp constants in Fourier restriction inequalities #2 DESCRIPTION:The Fourier restriction inequalities originate from the work of Stein\, Tomas\, Strichartz and Sigal in the 1970s\, and imposed themselves as a cornerstone of modern harmonic analysis. In these three talks we will present the state of the art for the problem of determining these inequalities in sharp form\, that is\, with best possible constants and knowledge of the functions which attain them. We will explore a selection of recent results with detailed proofs. URL:https://www.math.ens.psl.eu/evenement/cours-de-giuseppe-negro-n2/ LOCATION:DMA – Salle R3\, 45 rue d'Ulm\, Paris\, 75005\, France CATEGORIES:Séminaire interne de l'équipe d'analyse END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20250121T140000 DTEND;TZID=Europe/Paris:20250121T150000 DTSTAMP:20260425T164717 CREATED:20250117T125856Z LAST-MODIFIED:20250117T125856Z UID:18879-1737468000-1737471600@www.math.ens.psl.eu SUMMARY:Séminaire des doctorants / post-doctorants du CSD : Marien Renaud DESCRIPTION:Title: Plug-and-Play image restoration with Stochastic deNOising REgularization.\n  \nAbstract: Plug-and-Play (PnP) algorithms are a class of iterative algorithms that address image inverse problems by combining a physical model and a deep neural network for regularization. Even if they produce impressive image restoration results\, these algorithms rely on a non-standard use of a denoiser on images that are less and less noisy along the iterations\, which contrasts with recent algorithms based on Diffusion Models (DM)\, where the denoiser is applied only on re-noised images. In this presentation\, we propose a new PnP framework\, called Stochastic deNOising REgularization (SNORE)\, which applies the denoiser only on images with noise of the adequate level. It is based on an explicit stochastic regularization\, which leads to a stochastic gradient descent algorithm to solve ill-posed inverse problems. SNORE can be interpreted as imposing equivariance on the underlying prior. A convergence analysis of this algorithm and its proximal extension are provided. Experimentally\, we prove that SNORE is competitive with respect to state-of-the-art methods on deblurring and inpainting tasks\,both quantitatively and qualitatively.\n  URL:https://www.math.ens.psl.eu/evenement/seminaire-des-doctorants-post-doctorants-du-csd-marien-renaud/ LOCATION:CSD Conference room CATEGORIES:CSD seminar END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20250122T104500 DTEND;TZID=Europe/Paris:20250122T114500 DTSTAMP:20260425T164717 CREATED:20241126T135701Z LAST-MODIFIED:20250104T094923Z UID:18704-1737542700-1737546300@www.math.ens.psl.eu SUMMARY:Sharp constants in Fourier restriction inequalities #3 DESCRIPTION:The Fourier restriction inequalities originate from the work of Stein\, Tomas\, Strichartz and Sigal in the 1970s\, and imposed themselves as a cornerstone of modern harmonic analysis. In these three talks we will present the state of the art for the problem of determining these inequalities in sharp form\, that is\, with best possible constants and knowledge of the functions which attain them. We will explore a selection of recent results with detailed proofs. URL:https://www.math.ens.psl.eu/evenement/cours-de-giuseppe-negro-n3/ LOCATION:DMA – Salle R3\, 45 rue d'Ulm\, Paris\, 75005\, France CATEGORIES:Séminaire interne de l'équipe d'analyse END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20250123T120000 DTEND;TZID=Europe/Paris:20250123T130000 DTSTAMP:20260425T164717 CREATED:20250117T125403Z LAST-MODIFIED:20250117T125404Z UID:18877-1737633600-1737637200@www.math.ens.psl.eu SUMMARY:ENS-Data Science colloquium - Michele Ceriotti (EPFL) DESCRIPTION:Michele Ceriotti (EPFL) \n\n\n\nTitle: Between physics and scaling: inductive biases in atomistic machine learningAbstract: Machine-learning techniques are often applied to perform « end-to-end » predictions\, making black-box estimatesof a property of interest using only a coarse description of the corresponding inputs.In contrast\, atomic-scale modeling of matter is most useful when it allows one to gather a mechanistic insightinto the microscopic processes that underlie the behavior of molecules and materials.In this talk I will provide an overview of the progress that has been made combining these two philosophies\,using data-driven techniques to build surrogate models of the quantum mechanical behavior of atoms\, enabling« bottom-up » simulations that reveal the behavior of matter in realistic conditions with uncompromising accuracy.I will critically discuss two ways by which physical-chemical ideas can be integrated into a machine-learningframework. One way involves using physical priors\, such as smoothness or symmetry of the structure-propertyrelations\, to inform the mathematical structure of a generic ML approximation – an approach that has becomeubiquitous in the field\, but that is increasingly challenged by the emergence of unconstrained models that candirectly learn physical constraints from large amounts of data. The other entails a deeper level of integration\,in which explicit physics-based models and approximations are built into the model architecture.I will discuss several examples of the application of these ideas\, from the calculation of electronic excitationsto the design of solid-state electrolyte materials for batteries and high-entropy alloys for catalysis\, emphasizingboth the accuracy and the interpretability that can be achieved with a hybrid modeling approach\, and providing anoverview of the exciting research directions that are made available by these new modeling tools. \n\n\n\n \n\n\n\nThese seminars are being made possible through the support of the CFM-ENS Chair « Modèles et Sciences des Données ». \n\n\n\nThe organizers: Giulio Biroli\, Alex Cayco Gajic\, Bruno Loureiro\, Stéphane Mallat\, Gabriel Peyré. URL:https://www.math.ens.psl.eu/evenement/ens-data-science-colloquium-michele-ceriotti-epfl/ LOCATION:ENS Salle Dussane CATEGORIES:Séminaire Data de l’ENS END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20250127T110000 DTEND;TZID=Europe/Paris:20250127T120000 DTSTAMP:20260425T164717 CREATED:20241204T141736Z LAST-MODIFIED:20250120T094619Z UID:18748-1737975600-1737979200@www.math.ens.psl.eu SUMMARY:Thibaut Lemoine : théorèmes limites pour les ensembles orthogonaux DESCRIPTION:Les projections aléatoires constituent une technique de réduction de dimension simple et efficace en apprentissage automatique non supervisé. Elles reposent sur l’existence de quasi-immersions pour un ensemble de points d’un espace euclidien de haute dimension vers un espace de dimension inférieure. Nous proposerons une présentation du lemme de Johnson-Lindenstrauss centrée sur la notion de variable sous-gaussienne\, puis nous discuterons de la meilleure manière de construire des projections simples\, et en particulier creuses. URL:https://www.math.ens.psl.eu/evenement/thibaut-lemoine-theoremes-limites-pour-les-ensembles-orthogonaux/ LOCATION:DMA Salle W CATEGORIES:Séminaire informel de probabilités END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20250129T110000 DTEND;TZID=Europe/Paris:20250129T120000 DTSTAMP:20260425T164717 CREATED:20250124T143655Z LAST-MODIFIED:20250124T143656Z UID:18907-1738148400-1738152000@www.math.ens.psl.eu SUMMARY:Simon André\, raconte-moi le problème de Tarski ! DESCRIPTION:Deux groupes sont dits élémentairement équivalents s’ils vérifient les mêmes énoncés du premier ordre\, c’est-à-dire les mêmes énoncés mathématiques dont les variables désignent uniquement des éléments d’un groupe. Dans les années 40\, Tarski a posé la question suivante : les groupes libres de rang au moins deux sont-ils élémentairement équivalents ? Cette question est longtemps restée ouverte\, et ce n’est qu’au début des années 2000 qu’une réponse affirmative a finalement été apportée par Sela et par Kharlampovich et Myasnikov dans deux séries de travaux volumineuses. Dans mon exposé\, je présenterai ce résultat ainsi que sa généralisation naturelle aux groupes hyperboliques au sens de Gromov. URL:https://www.math.ens.psl.eu/evenement/simon-andre-raconte-moi-le-probleme-de-tarski/ LOCATION:DMA Salle W CATEGORIES:Algèbre et géométrie,Séminaire Raconte-moi END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20250129T170000 DTEND;TZID=Europe/Paris:20250129T180000 DTSTAMP:20260425T164717 CREATED:20250124T150404Z LAST-MODIFIED:20250124T150709Z UID:18916-1738170000-1738173600@www.math.ens.psl.eu SUMMARY:Paul Wang : Théorie catégorique des systèmes DESCRIPTION:Qu’est-ce qu’un système ? Dans quelle mesure est-il possible d’étudier un système en le décomposant en sous-systèmes ? La théorie catégorique des systèmes\, que j’illustrerai (sans utiliser de notions techniques !) avec l’exemple des systèmes déterministes à temps discret\, vise à fournir des réponses à ces questions. URL:https://www.math.ens.psl.eu/evenement/paul-wang-theorie-categorique-des-systemes/ LOCATION:Salle W CATEGORIES:Colloquium doctorant END:VEVENT END:VCALENDAR