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:20180325T010000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET DTSTART:20181028T010000 END:STANDARD BEGIN:DAYLIGHT TZOFFSETFROM:+0100 TZOFFSETTO:+0200 TZNAME:CEST DTSTART:20190331T010000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET DTSTART:20191027T010000 END:STANDARD TZID:UTC BEGIN:STANDARD TZOFFSETFROM:+0000 TZOFFSETTO:+0000 TZNAME:UTC DTSTART:20180101T000000 END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20190115T160000 DTEND;TZID=Europe/Paris:20190115T173000 DTSTAMP:20260422T015700 CREATED:20190115T150000Z LAST-MODIFIED:20211104T111400Z UID:8481-1547568000-1547573400@www.math.ens.psl.eu SUMMARY:Density of the union of Cartan subgroups of o-minimal groups DESCRIPTION:Let G be a group. A subgroup H of G is a Cartan subgroup ofG if H is a maximal nilpotent subgroup of G\, and for every normal finiteindex subgroup X of H\, X has finite index in its normalizer in G. \nWe consider Cartan subgroups of definably connect groups definable inan o-minimal structure. In [BJ0] we proved that\, in this context\,Cartan subgroups of G exist\, they are definable and they fall infinitely many conjugacy classes. \nIn this talk I will prove that the union of the Cartan subgroups isdense in the group\, which was the main question left open in [BBO].(Joint work with Elías Baro and Alessandro Berarducci.) \n [BJ0] E.Baro\, E. Jaligot and M.Otero. Cartan subgroups of groupsdefinable in o-minimal structures\, J. Inst. Math. Juissieu 13 no. 4(2014) 849 – 893. URL:https://www.math.ens.psl.eu/evenement/density-of-the-union-of-cartan-subgroups-of-o-minimal-groups/ LOCATION:Sophie Germain salle 2015 CATEGORIES:Théorie des Modèles et Groupes END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20190111T160000 DTEND;TZID=Europe/Paris:20190111T173000 DTSTAMP:20260422T015700 CREATED:20190111T150000Z LAST-MODIFIED:20211104T111600Z UID:8484-1547222400-1547227800@www.math.ens.psl.eu SUMMARY:Tame open core and small groups in pairs of topological geometric structures DESCRIPTION:Using the group configuration theorem\, Hrushovski and Pillay showed that the law of a group definable in the reals or the p-adics is locally an algebraic group law\, up to definable isomorphism. There are some natural expansions of these two theories of fields\, by adding a predicate for a dense substructure\, for example the algebraic reals or the algebraic p-adics. We will present an overview on some of the features of these expansions\, and particularly on the characterisation of open definable sets as well as of groups definable in the pairs. URL:https://www.math.ens.psl.eu/evenement/tame-open-core-and-small-groups-in-pairs-of-topological-geometric-structures/ LOCATION:ENS Salle W CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20190111T141500 DTEND;TZID=Europe/Paris:20190111T154500 DTSTAMP:20260422T015700 CREATED:20190111T131500Z LAST-MODIFIED:20211104T111400Z UID:8482-1547216100-1547221500@www.math.ens.psl.eu SUMMARY:Definability in the infinitesimal subgroup of a simple compact Lie group DESCRIPTION:Joint work with Kobi Peterzil.Let G be a simple compact Lie group\, for example G=SO_3(R). We consider the structure of definable sets in the subgroup G^{00} of infinitesimal elements. In an aleph_0-saturated elementary extension of the real field\, G^{00} is the inverse image of the identity under the standard part map\, so is definable in the corresponding valued field. We show that the pure group structure on G^{00} recovers the valued field\, making this a bi-interpretation. Hence the definable sets in the group are as rich as possible. URL:https://www.math.ens.psl.eu/evenement/definability-in-the-infinitesimal-subgroup-of-a-simple-compact-lie-group/ LOCATION:ENS Salle W CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20190111T110000 DTEND;TZID=Europe/Paris:20190111T123000 DTSTAMP:20260422T015700 CREATED:20190111T100000Z LAST-MODIFIED:20211104T111559Z UID:8483-1547204400-1547209800@www.math.ens.psl.eu SUMMARY:Scrollar invariants\, resolvents\, and syzygies DESCRIPTION:With every cover C -> P^1 of the projective line one can associate its so-called scrollar invariants (also called Maroni invariants) which describe how the push-forward of the structure sheaf of C splits over P^1. They can be viewed as geometric counterparts of the successive minima of the lattice associated with the ring of integers of a number field. In this talk we consider the following problem: how do the scrollar invariants of the Galois closure C’ -> P^1 and of its various subcovers (the so-called resolvents of C -> P^1) relate to known invariants of the given cover? This concerns ongoing work with Yongqiang Zhao\, in which we put a previous observation for covers of degree 4 due to Casnati in a more general framework. As we will see the answer involves invariants related to syzygies that were introduced by Schreyer. As time permits\, we will discuss a number-theoretic manifestation of the phenomena observed. URL:https://www.math.ens.psl.eu/evenement/scrollar-invariants-resolvents-and-syzygies/ LOCATION:ENS Salle W CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20190110T160000 DTEND;TZID=Europe/Paris:20190110T173000 DTSTAMP:20260422T015700 CREATED:20190110T150000Z LAST-MODIFIED:20211104T112500Z UID:14063-1547136000-1547141400@www.math.ens.psl.eu SUMMARY:Sous-groupes qui pavent génériquement et géométrie des involutions DESCRIPTION:(En collaboration avec Joshua Wiscons)L’exposé mélange théorie des modèles\, théorie des groupes\, et algèbre géométrique. On y parlera de groupes de rang de Morley fini\, mais il suffit de savoir naïvement ce qu’est une dimension à valeurs entières\, sans devoir maîtriser les finesses de la conjecture de Cherlin-Zilber.Un groupe abstrait porte peu d’information de nature géométrique\, même au sens des géométries d’incidence\, et c’est toujours remarquable si cela se produit.Le pur groupe SO(3\,R)\, par exemple\, permet de redéfinir l’espace projectif réel. PGL(2\,C) permet presque la même chose : il définit un fragment générique de l’espace projectif complexe. En fait cette situation est naturellement liée à la distribution des involutions et aux intersections entre conjugués de leur centralisateur\, qui pavent génériquement le groupe ambiant (tout cela sera expliqué dans SO(3\,R) et PGL(2\,C)).En suivant cette piste on peut obtenir des énoncés étonnamment forts\, généralisant au passage divers classiques sur les mauvais groupes ou sur les groupes définissablement linéaires de rang de Morley fini. On conjecture également que cette géométrie des involutions annonce un nouveau théorème d’identification pour PGL(2\, K). URL:https://www.math.ens.psl.eu/evenement/sous-groupes-qui-pavent-generiquement-et-geometrie-des-involutions-2/ CATEGORIES:Théorie des Modèles et Groupes END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181218T160000 DTEND;TZID=Europe/Paris:20181218T173000 DTSTAMP:20260422T015700 CREATED:20181218T150000Z LAST-MODIFIED:20211104T111158Z UID:8475-1545148800-1545154200@www.math.ens.psl.eu SUMMARY:Les groupes virtuellement libres sont presque homogènes DESCRIPTION:Perin et Sklinos\, et indépendamment Ould Houcine\, ont démontré en 2011 que les groupes libres sont homogènes : deux éléments qui ont le même type sont dans la même orbite sous l’action du groupe d’automorphismes. Dans cet exposé\, j’expliquerai que ce résultat reste presque vrai pour les groupes virtuellement libres\, au sens suivant : l’ensemble des éléments ayant le même type qu’un élément donné contient un nombre fini d’orbites sous le groupe d’automorphismes\, et ce nombre ne dépend pas de l’élément considéré. J’expliquerai également pourquoi je pense que ce résultat est optimal\, en donnant un exemple de groupe virtuellement libre dont je conjecture qu’il n’est pas homogène (travail en cours). URL:https://www.math.ens.psl.eu/evenement/les-groupes-virtuellement-libres-sont-presque-homogenes/ LOCATION:Sophie Germain salle 2015 CATEGORIES:Théorie des Modèles et Groupes END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181214T160000 DTEND;TZID=Europe/Paris:20181214T173000 DTSTAMP:20260422T015700 CREATED:20181214T150000Z LAST-MODIFIED:20211104T111159Z UID:8477-1544803200-1544808600@www.math.ens.psl.eu SUMMARY:On differentially large fields. DESCRIPTION:Recall that a field K is large if it is existentially closed in K((t)). Examples of such fields are the complex\, the real\, and the p-adic numbers. This class of fields has been exploited significantly by F. Pop and others in inverse Galois-theoretic problems. In recent work with M. Tressl we introduced and explored a differential analogue of largeness\, that we conveniently call « differentially large ». I will present some properties of such fields\, and use a twisted version of the Taylor morphism to characterise them using formal Laurent series and to even construct « natural » examples (which ultimately yield examples of DCFs and CODFs… acronyms that will be explained in the talk). URL:https://www.math.ens.psl.eu/evenement/on-differentially-large-fields/ LOCATION:ENS Salle W CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181214T110000 DTEND;TZID=Europe/Paris:20181214T123000 DTSTAMP:20260422T015700 CREATED:20181214T100000Z LAST-MODIFIED:20211104T111358Z UID:8478-1544785200-1544790600@www.math.ens.psl.eu SUMMARY:Uniform bound for points of bounded degree in function fields of positive characteristic DESCRIPTION:I will present a bound for the number of F_q[t]-points of bounded degree in a variety defined over Z[t]\, uniform in q. This generalizes work by Sedunova for fixed q. The proof involves model theory of valued fields with algebraic Skolem functions and uniform non-Archimedean Yomdin-Gromov parametrizations. This is joint work with Raf Cluckers and François Loeser. URL:https://www.math.ens.psl.eu/evenement/uniform-bound-for-points-of-bounded-degree-in-function-fields-of-positive-characteristic/ LOCATION:ENS Salle W CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181213T141500 DTEND;TZID=Europe/Paris:20181213T154500 DTSTAMP:20260422T015700 CREATED:20181213T131500Z LAST-MODIFIED:20211104T111359Z UID:8480-1544710500-1544715900@www.math.ens.psl.eu SUMMARY:Ax-Lindemann-Weierstrass with derivatives and the genus 0 Fuchsian groups DESCRIPTION:We prove the Ax-Lindemann-Weierstrass theorem for the uniformizing functions of genus zero Fuchsian groups of the first kind. Our proof relies on differential Galois theory of Schwarzian equations and machinery from the model theory of differentially closed fields. This result generalizes previous work of Pila-Tsimerman on the j function. (Joint work with James Freitag and Joel Nagloo) URL:https://www.math.ens.psl.eu/evenement/ax-lindemann-weierstrass-with-derivatives-and-the-genus-0-fuchsian-groups/ LOCATION:ENS Salle W CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181211T140000 DTEND;TZID=Europe/Paris:20181211T170000 DTSTAMP:20260422T015700 CREATED:20181211T130000Z LAST-MODIFIED:20211104T111359Z UID:8479-1544536800-1544547600@www.math.ens.psl.eu SUMMARY:Après-midi de théorie de groupes DESCRIPTION:14.00-14.45 Dawid Kielak (Bielefeld)Fibring of residually finite rationally-solvable groups14.45 -15.15 coffee break15.15-16.00 Damian Osajda (Wroclaw and McGill\, Montreal)A combination theorem for combinatorially non-positively curved complxes of hyperbolic groups URL:https://www.math.ens.psl.eu/evenement/apres-midi-de-theorie-de-groupes-2/ LOCATION:Salle W CATEGORIES:Séminaire de théorie des groupes à l’ENS END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181204T160000 DTEND;TZID=Europe/Paris:20181204T173000 DTSTAMP:20260422T015700 CREATED:20181204T150000Z LAST-MODIFIED:20211104T111159Z UID:8476-1543939200-1543944600@www.math.ens.psl.eu SUMMARY:Sous-groupe additif générique d'un corps algébriquement clos de caractéristique positive. DESCRIPTION:La théorie d’un corps algébriquement clos de caractéristique positive p muni d’un prédicat pour un sous-groupe additif admet une modèle-compagne ACF_pG. On se propose de décrire ce nouvel exemple de théorie NSOP_1\, en décrivant les imaginaires\, le Kim-forking et le forking. On parlera aussi de la généralisation de cette construction afin de présenter de nouveaux exemples de théories NSOP_1. URL:https://www.math.ens.psl.eu/evenement/sous-groupe-additif-generique-dun-corps-algebriquement-clos-de-caracteristique-positive/ LOCATION:Sophie Germain salle 2015 CATEGORIES:Théorie des Modèles et Groupes END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181120T160000 DTEND;TZID=Europe/Paris:20181120T173000 DTSTAMP:20260422T015700 CREATED:20181120T150000Z LAST-MODIFIED:20211104T110958Z UID:8470-1542729600-1542735000@www.math.ens.psl.eu SUMMARY:Counting in pseudofinite structures DESCRIPTION:In pseudofinite structures\, the non-standard size of definable sets often reveals important algebraic or model theoretic properties of the corresponding theories. In this talk\, we will give two new examples of this correlation. One is between the coarse dimension and the transformal transcendental degree in certain class of pseudofinite difference fields. The other example is that in pseudofinite H-strucures which are built from one-dimensional asymptotic classes\, the coarse dimension of a tuple corresponds to the coefficient of the leading term of SU-rank of this tuple. This is the first step to show that they are examples of multidimensional asymptotic classes (mac). URL:https://www.math.ens.psl.eu/evenement/counting-in-pseudofinite-structures/ LOCATION:Salle 2015 Sophie Germain CATEGORIES:Théorie des Modèles et Groupes END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181116T160000 DTEND;TZID=Europe/Paris:20181116T173000 DTSTAMP:20260422T015700 CREATED:20181116T150000Z LAST-MODIFIED:20211104T111157Z UID:8473-1542384000-1542389400@www.math.ens.psl.eu SUMMARY:Oscillatory integrals of subanalytic functions DESCRIPTION:In several papers\, R. Cluckers and D. Miller have built and investigated a class of real functions which contains the subanalytic functions and which is closed under parameterized integration. This class does not allow any oscillatory behavior\, nor stability under Fourier transform. On the other hand\, the behavior of oscillatory integrals\, in connection with singularity theory\, has been heavily investigated for decades. In this talk\, we explain how to build a class of complex functions\, which contains the subanalytic functions and their complex exponentials\, and which is closed under parameterized integration and under Fourier transform.Our techniques involve appropriate preparation theorems for subanalytic functions\, and some elements of the theory of uniformly distributed families of maps.(joint work with R. Clucker\, G. Comte\, D. Miller and T. Servi). URL:https://www.math.ens.psl.eu/evenement/oscillatory-integrals-of-subanalytic-functions/ LOCATION:ENS Salle W CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181116T141500 DTEND;TZID=Europe/Paris:20181116T154500 DTSTAMP:20260422T015700 CREATED:20181116T131500Z LAST-MODIFIED:20211104T110958Z UID:8472-1542377700-1542383100@www.math.ens.psl.eu SUMMARY:First-order logic in finitely generated fields DESCRIPTION:The expressive power of first-order logic in the class of finitely generated fields\, as structures in the language of rings\, is relatively poorly understood. For instance\, Pop asked in 2002 whether elementarily equivalent finitely generated fields are necessarily isomorphic\, and this is still not known in the general case. On the other hand\, the related situation of finitely generated rings is much better understood by recent work of Aschenbrenner-Khélif-Naziazeno-Scanlon.Building on work of Pop and Poonen\, and using geometric results due to Kerz-Saito and Gabber\, I shall show that every infinite finitely generated field of characteristic not two admits a definable subring which is a finitely generated algebra over a global field. This implies that any such finitely generated field is biinterpretable with arithmetic\, and gives a positive answer to the question above in characteristic not two. URL:https://www.math.ens.psl.eu/evenement/first-order-logic-in-finitely-generated-fields/ LOCATION:ENS Salle W CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181116T110000 DTEND;TZID=Europe/Paris:20181116T123000 DTSTAMP:20260422T015700 CREATED:20181116T100000Z LAST-MODIFIED:20211104T110958Z UID:8471-1542366000-1542371400@www.math.ens.psl.eu SUMMARY:Non-standard analysis and non-archimedean geometry DESCRIPTION:In this talk I will describe a joint work (still in progress) with E. Hrushovski and F. Loeser\, in which we explain how the integrals I have defined with Chambert-Loir on Berkovich spaces can beseen (in the t-adic case) as limits of usual integrals on complex algebraic varieties URL:https://www.math.ens.psl.eu/evenement/non-standard-analysis-and-non-archimedean-geometry/ LOCATION:ENS Salle W CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181113T160000 DTEND;TZID=Europe/Paris:20181113T173000 DTSTAMP:20260422T015700 CREATED:20181113T150000Z LAST-MODIFIED:20211104T110957Z UID:8469-1542124800-1542130200@www.math.ens.psl.eu SUMMARY:Groupes et anneaux oméga-catégoriques de fardeau fini DESCRIPTION:Les groupes de fardeau fini sont les groupes NTP_2 qui correspondent aux groupes stables ou simples de rang fini. Or\, le fardeau est plus difficile à manipuler car il n’est pas forcément additif par fibration. Nous montrons que ces groupes sont virtuellement abélien-par-fini\, et les anneaux sont virtuellement fini-par-nuls. Ceci améliore un résultat de Kaplan\, Levi et Simon qui avaient démontré qu’un groupe dp-minimal est virtuellement nilpotent.Travail en commun avec Jan Dobrowolski URL:https://www.math.ens.psl.eu/evenement/groupes-et-anneaux-omega-categoriques-de-fardeau-fini/ LOCATION:Salle 2015 Sophie Germain CATEGORIES:Théorie des Modèles et Groupes END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181113T140000 DTEND;TZID=Europe/Paris:20181113T140000 DTSTAMP:20260422T015700 CREATED:20181113T130000Z LAST-MODIFIED:20211104T111158Z UID:8474-1542117600-1542117600@www.math.ens.psl.eu SUMMARY:Après-midi de théorie de groupes DESCRIPTION:Tuesday\, 13 November14.00-14.45 Miklos Abert (Renyi Institute Budapest)15.00-15.45 Arman Darbinyan (ENS Paris)15.45-15.15 coffee break16.15-17.00 Rachel Skipper (Göttingen and ENS Lyon) URL:https://www.math.ens.psl.eu/evenement/apres-midi-de-theorie-de-groupes/ LOCATION:Salle W CATEGORIES:Séminaire de théorie des groupes à l’ENS END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20181009T140000 DTEND;TZID=Europe/Paris:20181009T170000 DTSTAMP:20260422T015700 CREATED:20181009T120000Z LAST-MODIFIED:20211119T102754Z UID:8468-1539093600-1539104400@www.math.ens.psl.eu SUMMARY:Après-midi de théorie des groupes DESCRIPTION:14.00-14.45 Martin Bridson (Oxford)\, Profinite rigidity and hyperbolic 3-orbifolds15.00-15.45 Arnaud Hilion (Marseille): Boundary of cyclic hyperbolic extensions of free groups15.45-16.15 pause café16.15-17.00 Damien Gaboriau (ENS Lyon)\, On non-vanishing of the cohomology of Aut(Fn) and Out(Fn) in top dimensions URL:https://www.math.ens.psl.eu/evenement/apres-midi-de-theorie-des-groupes-2/ LOCATION:ENS 45 rue d’Ulm salle W toits du DMA CATEGORIES:Séminaire de théorie des groupes à l’ENS END:VEVENT BEGIN:VEVENT DTSTART;TZID=UTC:20180807T080000 DTEND;TZID=UTC:20180807T080000 DTSTAMP:20260422T015700 CREATED:20180807T060000Z LAST-MODIFIED:20211015T074123Z UID:557-1533628800-1533628800@www.math.ens.psl.eu SUMMARY:Science Nature Day DESCRIPTION:Lorem ipsum oin gravida nibh vel veliauctor aliquenean sollicitudin\, lorem quis bibendum auctor\, nisi elit consequat ipsutis sem nibh id elit. Duis sed odio sit amet nibh vulputate cursus a sit amet mauris. Morbi accumsan ipsum velit. Nam nec tellus a odio tincidunt auctor a ornare odio. Sed non mauris vitae erat consequat auctor eu in elit. Class aptent taciti sociosqu ad litora torquent per conubia nostra\, per inceptos himenaeos. Mauris in erat justo. Nullam ac urna eu felis dapibus condimentum sit amet a augue. Sed non neque elit. Sed ut imperdiet nisi. Proin condimentum fermentum nunc. URL:https://www.math.ens.psl.eu/evenement/science-nature-day/ CATEGORIES:Variétés rationnelles END:VEVENT BEGIN:VEVENT DTSTART;TZID=UTC:20180720T120000 DTEND;TZID=UTC:20180720T120000 DTSTAMP:20260422T015700 CREATED:20180720T100000Z LAST-MODIFIED:20211015T074129Z UID:807-1532088000-1532088000@www.math.ens.psl.eu SUMMARY:Painting Festival DESCRIPTION:Lorem ipsum oin gravida nibh vel veliauctor aliquenean sollicitudin\, lorem quis bibendum auctor\, nisi elit consequat ipsutis sem nibh id elit. Duis sed odio sit amet nibh vulputate cursus a sit amet mauris. Morbi accumsan ipsum velit. Nam nec tellus a odio tincidunt auctor a ornare odio. Sed non mauris vitae erat consequat auctor eu in elit. Class aptent taciti sociosqu ad litora torquent per conubia nostra\, per inceptos himenaeos. Mauris in erat justo. Nullam ac urna eu felis dapibus condimentum sit amet a augue. Sed non neque elit. Sed ut imperdiet nisi. Proin condimentum fermentum nunc. URL:https://www.math.ens.psl.eu/evenement/painting-festival/ CATEGORIES:Variétés rationnelles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20180626T140000 DTEND;TZID=Europe/Paris:20180626T180000 DTSTAMP:20260422T015700 CREATED:20180626T120000Z LAST-MODIFIED:20211104T110755Z UID:8464-1530021600-1530036000@www.math.ens.psl.eu SUMMARY:Après-midi de théorie des groupes DESCRIPTION:14.00-14.45 Pierre Pansu (Orsay) L^1 cohomology of Euclidean spaces andHeisenberg groups15.00-15.45  Tianyi Zhang  (UC San Diego) Growth of torsion Grigorchukgroups15.45-16.15 pause café16.15-17.00  Sergei Ivanov (St-Petersbourg)\, Transfinite invariants ofgroups and spaces17.15-18.00 Kate Juschenko (Northwestern University)\, On Liouvilleproperty of action of discrete groups URL:https://www.math.ens.psl.eu/evenement/apres-midi-de-theorie-des-groupes/ LOCATION:Institut Henri Poincaré (11 rue Pierre et Marie Curie 75005 Paris) salle 01 CATEGORIES:Séminaire de théorie des groupes à l’ENS END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20180619T160000 DTEND;TZID=Europe/Paris:20180619T173000 DTSTAMP:20260422T015700 CREATED:20180619T140000Z LAST-MODIFIED:20211104T110755Z UID:8463-1529424000-1529429400@www.math.ens.psl.eu SUMMARY:Corps interprétables dans ACVF DESCRIPTION:(Travail en commun avec E. Hrushovski)Le but de cet exposé sera de montrer qu’il n’y a que deux corps interprétables (à isomorphisme définissable près) dans ACVF. On commencera par rappeler des résultats de classification des groupes (abéliens) interprétables dans ACVF puis on appliquera ces résultats à l’étude des corps. URL:https://www.math.ens.psl.eu/evenement/corps-interpretables-dans-acvf/ LOCATION:Sophie Germain salle 1016 CATEGORIES:Théorie des Modèles et Groupes END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20180518T160000 DTEND;TZID=Europe/Paris:20180518T173000 DTSTAMP:20260422T015700 CREATED:20180518T140000Z LAST-MODIFIED:20211104T110740Z UID:8460-1526659200-1526664600@www.math.ens.psl.eu SUMMARY:Doubling parametrizations and Remez-type inequalities DESCRIPTION:A doubling chart on an n-dimensional complex manifold Y is a univalent analytic mapping psi : B_1 URL:https://www.math.ens.psl.eu/evenement/doubling-parametrizations-and-remez-type-inequalities/ LOCATION:Jussieu salle 101 couloir 15-16 (1er étage)4 place Jussieu CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20180518T141500 DTEND;TZID=Europe/Paris:20180518T154500 DTSTAMP:20260422T015700 CREATED:20180518T121500Z LAST-MODIFIED:20211104T110741Z UID:8461-1526652900-1526658300@www.math.ens.psl.eu SUMMARY:Isotrivial Mordell-Lang and finite automata DESCRIPTION:About fifteen years ago\, Thomas Scanlon and I gave a description of sets that arise as the intersection of a subvariety with a finitely generated subgroup inside a semiabelian variety over a finite field. Inspired by later work of Derksen on the positive characteristic Skolem-Mahler-Lech theorem\, which turns out to be a special case\, Jason Bell and I have recently recast those results in terms of finite automata. I will report on this work\, as well as on the work-in-progress it has engendered on an effective version of the isotrivial Mordell-Lang theorem. URL:https://www.math.ens.psl.eu/evenement/isotrivial-mordell-lang-and-finite-automata/ LOCATION:Jussieu salle 101 couloir 15-16 (1er étage)4 place Jussieu CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20180518T110000 DTEND;TZID=Europe/Paris:20180518T123000 DTSTAMP:20260422T015700 CREATED:20180518T090000Z LAST-MODIFIED:20211104T110740Z UID:8459-1526641200-1526646600@www.math.ens.psl.eu SUMMARY:Groups and algebras DESCRIPTION:To every group G is associated an associative algebra\, namely its group ring kG. Which (geometric) properties are reflected in (algebraic) properties of kG? I will survey some results and conjectures in this area\, concentrating on specific examples: growth\, amenability\, torsion\, and filtrations. URL:https://www.math.ens.psl.eu/evenement/groups-and-algebras/ LOCATION:Jussieu salle 101 couloir 15-16 (1er étage)4 place Jussieu CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20180515T140000 DTEND;TZID=Europe/Paris:20180515T170000 DTSTAMP:20260422T015700 CREATED:20180515T120000Z LAST-MODIFIED:20211104T110741Z UID:8462-1526392800-1526403600@www.math.ens.psl.eu SUMMARY:Mardi après-midi de théorie des groupes DESCRIPTION:14.00-14.45 Thomas Schick (Göttingen): Approximation of L2-Betti numbers and the algebraic Eigenvalue property (after Jaikin-Zaipirain)15.00-15.45 Jacques Darné (Lille): Variations autour du problème d’Andreadakis 15.45-16.15 pause café16.15-17.00 Volodymyr Nekrashevych (Texas A&M): Amenability of iterated monodromy groups URL:https://www.math.ens.psl.eu/evenement/mardi-apres-midi-de-theorie-des-groupes/ LOCATION:Salle W toits du DMA CATEGORIES:Séminaire de théorie des groupes à l’ENS END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20180427T163000 DTEND;TZID=Europe/Paris:20180427T173000 DTSTAMP:20260422T015700 CREATED:20180427T143000Z LAST-MODIFIED:20211104T110739Z UID:8458-1524846600-1524850200@www.math.ens.psl.eu SUMMARY:Applications of Morava K-theory to algebraic groups and quadrics. DESCRIPTION:For a prime number p and a non-negative integer n we consider a Morava K-theory K(n) with the coefficient ring ?p. This is a universal oriented cohomology theory in the sense of Levine-Morel with a pn-typical formal group law which has height n modulo p. It turns out that K(n) is strongly related to cohomological invariants of algebraic groups in the sense of Serre. This is our starting point to compute the Chow groups of quadrics from the powers Im+2 of the fundamental ideal of the Witt ring up to codimension 2m. Moreover\, the Morava K-theory gives a conceptional explanation of the nature of the obtained answer. This is a joint work with Pavel Sechin. URL:https://www.math.ens.psl.eu/evenement/applications-of-morava-k-theory-to-algebraic-groups-and-quadrics/ LOCATION:ENS Salle W CATEGORIES:Variétés rationnelles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20180427T150000 DTEND;TZID=Europe/Paris:20180427T160000 DTSTAMP:20260422T015700 CREATED:20180427T130000Z LAST-MODIFIED:20211104T110540Z UID:8457-1524841200-1524844800@www.math.ens.psl.eu SUMMARY:Noyaux d'Albanese et groupes de Griffiths. DESCRIPTION:On décrit le groupe de Griffiths du produit d’une courbe C et d’une surface S comme un quotient du noyau d’Albanese de S pris sur le corps des fonctions de C. Quand C est une section hyperplane de S variant dans un pinceau de Lefschetz\, une modification convenable du graphe du plongement de C dans S a une classe dans Griff(CxS). On démontre que cette classe est non nulle pour une infinité de membres du pinceau lorsque le corps de base k est de caractéristique 0\, que le genre géométrique de S est >0\, et que k est gros\, ou que S est de type abélien motivé. URL:https://www.math.ens.psl.eu/evenement/noyaux-dalbanese-et-groupes-de-griffiths/ LOCATION:ENS Salle W CATEGORIES:Variétés rationnelles END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20180417T140000 DTEND;TZID=Europe/Paris:20180417T170000 DTSTAMP:20260422T015700 CREATED:20180417T120000Z LAST-MODIFIED:20211104T110540Z UID:8456-1523973600-1523984400@www.math.ens.psl.eu SUMMARY:3 exposés de dynamique et théorie des groupes DESCRIPTION:14.00-14.45 Omer Tamuz (Caltech): The Poisson boundary and the infinite conjugacy class property15.00-15.45 Yair Hartman (Northwestern University): Stationary C*-Dynamical Systems15.45-16.15 pause café16.15-17.00 Said Sidki (University of Brasilia): Self-similarity and finite presentability URL:https://www.math.ens.psl.eu/evenement/3-exposes-de-dynamique-et-theorie-des-groupes-2/ LOCATION:Salle W toits du DMA ENS CATEGORIES:Séminaire de théorie des groupes à l’ENS END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20180323T160000 DTEND;TZID=Europe/Paris:20180323T173000 DTSTAMP:20260422T015700 CREATED:20180323T150000Z LAST-MODIFIED:20211104T110539Z UID:8455-1521820800-1521826200@www.math.ens.psl.eu SUMMARY:A model theoretic generalization of the one-dimensional case of the Elekes-Szabo theorem DESCRIPTION:(Joint work with A. Chernikov)Let V subseteq C^3 be a complex variety of dimension 2.The Elekes-Szabo Theorem says that if V contains `too many’ points on n x n x n Cartesian products then V has a special form: either V contains a cylinder over a curve or V is related to the graph of the multiplication of an algebraic group.In this talk we generalize the Elekes-Szabo Theorem to relations on strongly minimal sets interpretable in distal structures. URL:https://www.math.ens.psl.eu/evenement/a-model-theoretic-generalization-of-the-one-dimensional-case-of-the-elekes-szabo-theorem/ LOCATION:IHP amphitheatre Darboux CATEGORIES:Séminaire Géométrie et théorie des modèles END:VEVENT END:VCALENDAR