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PRODID:-//Département de mathématiques et applications - ECPv6.2.2//NONSGML v1.0//EN
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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
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TZID:Europe/Paris
BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:20220327T010000
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TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:20221030T010000
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BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20220301T160000
DTEND;TZID=Europe/Paris:20220301T173000
DTSTAMP:20260406T035057
CREATED:20220223T142159Z
LAST-MODIFIED:20220309T160937Z
UID:15319-1646150400-1646155800@www.math.ens.psl.eu
SUMMARY:Existentially closed measure-preserving actions of free groups
DESCRIPTION:I will discuss a joint work with Alexander Berenstein and Ward Henson\, in which we show that the theory of probability algebras with two automorphisms has a model completion\, which moreover has quantifier elimination and is stable. We also exhibit two non-isomorphic (but approximately isomorphic) models of the model completion.\nMore generally\, we give a sufficient set of conditions for the axiomatizability (in continuous logic) of the existentially closed actions of a free group on a separably categorical\, stable structure.\nI will also mention a number of open questions.
URL:https://www.math.ens.psl.eu/evenement/existentially-closed-measure-preserving-actions-of-free-groups/
LOCATION:Sophie Germain salle 1016.
CATEGORIES:Théorie des Modèles et Groupes
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20220309T110000
DTEND;TZID=Europe/Paris:20220309T120000
DTSTAMP:20260406T035057
CREATED:20220218T132131Z
LAST-MODIFIED:20220218T132131Z
UID:15310-1646823600-1646827200@www.math.ens.psl.eu
SUMMARY:Najib Idrissi\, raconte-moi les opérades !
DESCRIPTION:Les opérades sont des objets qui gouvernent des catégories d’algèbres au sens large — par exemple\, les algèbres associatives\, les algèbres commutatives\, ou les algèbres de Lie — qui sont habituellement définies par « opérations génératrices et relations ». Le but de cet exposé est d’introduire la théorie des opérades avec des exemples\, et en particulier l’exemple fondateur des opérades des petits disques. J’expliquerai comment les opérades des petits disques permettent d’obtenir des invariants des variétés de deux façons duales : le calcul des plongements et l’homologie de factorisation.
URL:https://www.math.ens.psl.eu/evenement/najib-idrissi-raconte-moi-les-operades/
LOCATION:En salle W au DMA\, ou sur Zoom
CATEGORIES:Algèbre et géométrie,Séminaire Raconte-moi
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20220315T140000
DTEND;TZID=Europe/Paris:20220315T170000
DTSTAMP:20260406T035057
CREATED:20220305T170139Z
LAST-MODIFIED:20220305T170529Z
UID:15335-1647352800-1647363600@www.math.ens.psl.eu
SUMMARY:Un après-midi de théorie des groupes
DESCRIPTION:Le séminaire sera dans salle W et retransmis sur Zoom : \nZOOM: https://us02web.zoom.us/j/82070470538\nID: 820 7047 0538\nMot de passe:\nG est un Graphe de Cayley du groupe libre à 107 générateurs. Quel est\nle degré de ce graphe? Tapez le numéro à trois chiffres comme un mot\nde passe. \n14.00 – 14.45 Marcin Sabok  (McGill University)\, « Hyperfiniteness at\nhyperbolic boundries » \n15.00 – 15.45 Juan Paucar (Jussieu)\, « Coarse embeddings between locally\ncompact groups and quantitative measured equivalence » \n16.00 – 16.45 Josh Frisch (ENS)\, « Characteristic Measures and Minimal\nSubdynamics » \nVous pourrez trouver les résumés sur le site du séminaire:\nhttps://sites.google.com/site/annaerschler/grseminar
URL:https://www.math.ens.psl.eu/evenement/un-apres-midi-de-theorie-des-groupes/
LOCATION:14:00-17:00 Salle W
CATEGORIES:Séminaire de théorie des groupes à l’ENS
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20220315T160000
DTEND;TZID=Europe/Paris:20220315T173000
DTSTAMP:20260406T035057
CREATED:20220309T160534Z
LAST-MODIFIED:20220309T160950Z
UID:15402-1647360000-1647365400@www.math.ens.psl.eu
SUMMARY:Curve-excluding fields
DESCRIPTION:Consider the class of fields with Char(K)=0 and x^4+y^4=1 has only 4 solutions in K\, we show that this class has a model companion\, which we denote by curve-excluding fields. Curve-excluding fields provides (counter)examples to various questions. Model theoretically\, they are model complete and TP_2. Field theoretically\, they are not large and unbounded. We will discuss other aspects such as decidability of such fields. This is joint work with Will Johnson and Erik Walsberg.
URL:https://www.math.ens.psl.eu/evenement/curve-excluding-fields-2/
LOCATION:salle 1016 Sophie Germain
CATEGORIES:Théorie des Modèles et Groupes
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20220318T140000
DTEND;TZID=Europe/Paris:20220318T153000
DTSTAMP:20260406T035057
CREATED:20220311T152633Z
LAST-MODIFIED:20220311T152633Z
UID:15421-1647612000-1647617400@www.math.ens.psl.eu
SUMMARY:Interdefinability and compatibility in certain o-minimal expansions of the real field
DESCRIPTION:Let us say that a real function f is o-minimal if the expansion (R\,f) of the real field by f is o-minimal. A function g is definable from f if g is definable in (R\,f). Two o-minimal functions are compatible if there exists an o-minimal expansion M of the real field in which they are both definable. I will discuss the o-minimality\, the interdefinability and the compatibility of two special functions\, Euler’s Gamma and Riemann’s Zeta\, restricted to the reals. If time allows it\, I will present a general technique for establishing whether a function is definable or not in a given o-minimal expansion of the reals. Joint work with J.-P. Rolin and P. Speissegger.
URL:https://www.math.ens.psl.eu/evenement/interdefinability-and-compatibility-in-certain-o-minimal-expansions-of-the-real-field/
LOCATION:Zoom
CATEGORIES:Séminaire Géométrie et théorie des modèles
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20220318T154500
DTEND;TZID=Europe/Paris:20220318T171500
DTSTAMP:20260406T035057
CREATED:20220318T144518Z
LAST-MODIFIED:20220311T152909Z
UID:15394-1647618300-1647623700@www.math.ens.psl.eu
SUMMARY:Tameness beyond o-minimality (in expansions of the real ordered additive group)
DESCRIPTION:In his influential paper “Tameness in expansions of the real field” from the early 2000s\, Chris Miller wrote: \n“ What might it mean for a first-order expansion of the field of real numbers to be tame or well behaved? In recent years\, much attention has been paid by model theorists and real-analytic geometers to the o-minimal setting: expansions of the real field in which every definable set has finitely many connected components. But there are expansions of the real field that define sets with infinitely many connected components\, yet are tame in some well-defined sense […]. The analysis of such structures often requires a mixture of model-theoretic\, analytic-geometric and descriptive set-theoretic techniques. An underlying idea is that first-order definability\, in combination with the field structure\, can be used as a tool for determining how complicated is a given set of real numbers.” \nMuch progress has been made since then\, and in this talk I will discuss an updated account of this research program. I will consider this program in the larger generality of expansions of the real ordered additive group (rather than just in expansions of the real field as envisioned by Miller). In particular\, I will mention in this context recent joint work with Erik Walsberg\, in which we produce an interesting tetrachotomy for such expansions.
URL:https://www.math.ens.psl.eu/evenement/tameness-beyond-o-minimality-in-expansions-of-the-real-ordered-additive-group/
LOCATION:Zoom
CATEGORIES:Séminaire Géométrie et théorie des modèles
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20220322T160000
DTEND;TZID=Europe/Paris:20220322T173000
DTSTAMP:20260406T035057
CREATED:20220317T152124Z
LAST-MODIFIED:20220317T152139Z
UID:15444-1647964800-1647970200@www.math.ens.psl.eu
SUMMARY:Lie groups definable in o-minimal theories
DESCRIPTION:In this talk we will work out a complete characterization of which Lie groups admit a “definable copy”. This is\, characterize for which Lie groups G one can find a group H definable in an o-minimal expansion of the real field\, and such that G and H are isomorphic.\nWhen the answer is positive\, the definable copy H that we find is definable in the language of exponential ordered fields\, and it is such that any Lie automorphism of H is definable.
URL:https://www.math.ens.psl.eu/evenement/lie-groups-definable-in-o-minimal-theories/
LOCATION:Sophie Germain salle 1016.
CATEGORIES:Théorie des Modèles et Groupes
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