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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:20170326T010000
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TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:20171029T010000
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BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20170210T110000
DTEND;TZID=Europe/Paris:20170210T110000
DTSTAMP:20260504T184154
CREATED:20170210T100000Z
LAST-MODIFIED:20211104T102528Z
UID:8341-1486724400-1486724400@www.math.ens.psl.eu
SUMMARY:Geometric invariants that are encoded in the Newton polygon
DESCRIPTION:Let k be a field and let P be a lattice polygon\, i.e. the convex hull in R^2 of finitely many non-collinear points of Z^2. Let C/k be the algebraic curve defined by a sufficiently generic Laurent polynomial that is supported on P. A result due to Khovanskii states that the geometric genus of C equals the number of Z^2-valued points that are contained in the interior of P. In this talk we will give an overview of various other curve invariants that can be told by looking at the combinatorics of P\, such as the gonality\, the Clifford index\, the Clifford dimension\, the scrollar invariants associated to a gonality pencil\, and in some special cases the canonical graded Betti numbers. This will cover joint work with Filip Cools\, Jeroen Demeyer and Alexander Lemmens.
URL:https://www.math.ens.psl.eu/evenement/geometric-invariants-that-are-encoded-in-the-newton-polygon/
LOCATION:ENS Salle W
CATEGORIES:Séminaire Géométrie et théorie des modèles
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20170210T141500
DTEND;TZID=Europe/Paris:20170210T141500
DTSTAMP:20260504T184154
CREATED:20170210T131500Z
LAST-MODIFIED:20211104T102727Z
UID:8342-1486736100-1486736100@www.math.ens.psl.eu
SUMMARY:Determining finite simple images of finitely presented groups
DESCRIPTION:I will discuss joint work with Martin Bridson and Martin Liebeck which addresses the question: for which collections of finite simple groups does there exist an algorithm that determines the images of an arbitrary finitely presented group that lie in the collection? We prove both positive and negative results. For a collection of finite simple groups that contains infinitely many alternating groups\, or contains classical groups of unbounded dimensions\, we prove that there is no such algorithm. On the other hand\, for a collection of simple groups of fixed Lie type we obtain positive results by using the model theory of finite fields.
URL:https://www.math.ens.psl.eu/evenement/determining-finite-simple-images-of-finitely-presented-groups/
LOCATION:ENS Salle W
CATEGORIES:Séminaire Géométrie et théorie des modèles
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20170210T160000
DTEND;TZID=Europe/Paris:20170210T160000
DTSTAMP:20260504T184154
CREATED:20170210T150000Z
LAST-MODIFIED:20211104T102728Z
UID:8343-1486742400-1486742400@www.math.ens.psl.eu
SUMMARY:Cell Decomposition for P-minimal structures: a story
DESCRIPTION:P-minimality is a concept that was developed by Haskell and Macpherson as a p-adic equivalent for o-minimality. For o-minimality\, the cell decomposition theorem is probably one of the most powerful tools\, so it is quite a natural question to ask for a p-adic equivalent of this.In this talk I would like to give an overview of the development of cell decomposition in the p-adic context\, with an emphasis on how questions regarding the existence of definable skolem functions have complicated things. The idea of p-adic cell decomposition was first developed by Denef\, for p-adic semi-algebraic structures\, as a tool to answer certain questions regarding quantifier elimination\, rationality and p-adic integration. This first version eventually resulted in a cell decomposition theorem for P-minimal structures. This theorem\, proven by Mourgues\, was however dependent on the existence of definable Skolem functions. The second part of the talk will focus a bit more on Skolem functions\, and sketch a generalized version of the Denef-Mourgues theorem that does not rely on the existence of such functions\, by introducing a notion of clustered cells. We will explain the notion\, give an informal sketch of the proof\, and compare with other versions of cell decomposition.
URL:https://www.math.ens.psl.eu/evenement/cell-decomposition-for-p-minimal-structures-a-story/
LOCATION:ENS Salle W
CATEGORIES:Séminaire Géométrie et théorie des modèles
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20170221T140000
DTEND;TZID=Europe/Paris:20170221T180000
DTSTAMP:20260504T184154
CREATED:20170221T130000Z
LAST-MODIFIED:20211104T103801Z
UID:8363-1487685600-1487700000@www.math.ens.psl.eu
SUMMARY:Quatre exposés en théorie des groupes
DESCRIPTION:
URL:https://www.math.ens.psl.eu/evenement/quatre-exposes-en-theorie-des-groupes/
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=Europe/Paris:20170221T160000
DTEND;TZID=Europe/Paris:20170221T160000
DTSTAMP:20260504T184154
CREATED:20170221T150000Z
LAST-MODIFIED:20211104T103600Z
UID:8358-1487692800-1487692800@www.math.ens.psl.eu
SUMMARY:Equationalité des paires de corps
DESCRIPTION:Une théorie est équationelle si tout ensemble définissable est combinaison booléenne d’instances d’équations\, c’est-à-dire des formules telles que la famille des intersections finies d’instances ont la propriété de chaîne descendante. L’équationalité\, introduite par Srour et ensuite étudiée par Pillay et Srour\, entraîne la stabilité. Or\, le seul exemple algébrique naturel d’une théorie stable non-équationelle est la théorie du groupe non-abélien libre\, comme récemment montré par Sela. Cependant\, ce n’est pas évident de montrer qu’une théorie stable donnée est équationelle. Cet exposé présentera les idées d’un travail en commun avec Martin Ziegler sur l’équationalité de la théorie des belles paires de corps algébriquement clos en toute caractéristique.
URL:https://www.math.ens.psl.eu/evenement/equationalite-des-paires-de-corps/
LOCATION:Sophie Germain salle 1016
CATEGORIES:Théorie des Modèles et Groupes
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20170224T150000
DTEND;TZID=Europe/Paris:20170224T160000
DTSTAMP:20260504T184154
CREATED:20170224T140000Z
LAST-MODIFIED:20211104T103801Z
UID:8365-1487948400-1487952000@www.math.ens.psl.eu
SUMMARY:Brauer groups and the Brauer-Manin sets of Kummer varieties.
DESCRIPTION:This is a joint work with Yuri Zarhin. We study Kummer varieties attached to 2-coverings of abelian varieties of arbitrary dimension. Over a number field we show that the subgroup of odd order elements of the Brauer group does not obstruct the Hasse principle. Sufficient conditions for the triviality of the Brauer group can be given\, which allow us to give an example of a Kummer K3 surface of geometric Picard rank 17 over the rationals with trivial Brauer group. We establish the non-emptyness of the Brauer-Manin set of everywhere locally soluble Kummer varieties attached to 2-coverings of products of hyperelliptic Jacobians with large Galois action on 2-torsion.
URL:https://www.math.ens.psl.eu/evenement/brauer-groups-and-the-brauer-manin-sets-of-kummer-varieties/
LOCATION:ENS Salle W
CATEGORIES:Variétés rationnelles
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20170224T163000
DTEND;TZID=Europe/Paris:20170224T173000
DTSTAMP:20260504T184154
CREATED:20170224T153000Z
LAST-MODIFIED:20211104T103802Z
UID:8366-1487953800-1487957400@www.math.ens.psl.eu
SUMMARY:Actions de p-groupes sur les variétés projectives.
DESCRIPTION:Je discuterai des contraintes que la géométrie d’une variété projective fait peser sur les possibles actions de p-groupes sur cette dernière. J’expliquerai en particulier comment le calcul d’invariants numériques\, tels que les nombres caractéristiques\, peut permettre de prévoir l’existence de points fixes.
URL:https://www.math.ens.psl.eu/evenement/actions-de-p-groupes-sur-les-varietes-projectives/
LOCATION:ENS Salle W
CATEGORIES:Variétés rationnelles
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20170228T160000
DTEND;TZID=Europe/Paris:20170228T160000
DTSTAMP:20260504T184154
CREATED:20170228T150000Z
LAST-MODIFIED:20211104T141026Z
UID:8359-1488297600-1488297600@www.math.ens.psl.eu
SUMMARY:Expansions minimales de (Z\,+\,0)
DESCRIPTION:Cet exposé essayera de donner une vision d’ensemble des différentes choses connu à ce jour sur les expansions du groupes des entiers (Z\,+\,0) avec un accent sur les expansions dp-minimales. En particulier les deux structures (Z\,+\,0\,
URL:https://www.math.ens.psl.eu/evenement/expansions-minimales-de-z0/
LOCATION:Sophie Germain salle 1016
CATEGORIES:Théorie des Modèles et Groupes
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