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X-WR-CALDESC:Évènements pour Laboratoire de Mathématiques de Versailles
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BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20221108T140000
DTEND;TZID=Europe/Paris:20221108T150000
DTSTAMP:20260525T090715
CREATED:20221027T104116Z
LAST-MODIFIED:20221110T084826Z
UID:11009-1667916000-1667919600@lmv.math.cnrs.fr
SUMMARY:AG : Ignacio Barros (University of Antwerp): The Kodaira classification of the moduli of hyperelliptic curves
DESCRIPTION:Abstract: We study the birational geometry of the moduli spaces of hyperelliptic curves with marked points. We show that these moduli spaces have non Q-factorial singularities. We complete the Kodaira classification by proving that these spaces have Kodaira dimension $4g+3$ when the number of markings is $4g+6$ and are of general type when the number of markings is $n\geq4g+7$. Similarly\, we consider the natural finite cover given by ordering the Weierstrass points. In this case\, we provide a full Kodaira classification showing that the Kodaira dimension is negative when $n\leq3$\, one when $n=4$\, and of general type when $n\geq 5$. For this\, we carry out a singularity analysis of a modular « almost » resolution given by Hurwitz spaces. We show that the ordered space has canonical singularities and the unordered space has non-canonical singularities. We describe all non-canonical points and show that pluricanonical forms defined on the full regular locus extend to any resolution. Further\, we provide a full classification of the structure of the pseudo-effective cone of Cartier divisors for the moduli space of hyperelliptic curves with marked points. We show the cone is non-polyhedral when the number of markings is at least two and polyhedral in the remaining cases. This is all joint work with S. Mullane.
URL:https://lmv.math.cnrs.fr/evenenement/ag-ignacio-barros-universitat-paderborn/
LOCATION:Bâtiment Fermat\, salle 4205
CATEGORIES:Séminaire AG
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20221115T140000
DTEND;TZID=Europe/Paris:20221115T150000
DTSTAMP:20260525T090715
CREATED:20221028T102155Z
LAST-MODIFIED:20221118T100425Z
UID:11021-1668520800-1668524400@lmv.math.cnrs.fr
SUMMARY:Leonardo Maltoni (LMV) : Vers une présentation de Bernstein de la catégorie de Hecke affine.
DESCRIPTION:Résumé : L’algèbre de Hecke affine admet une sous-algèbre commutative remarquable qui correspond au réseau des coracines dans le groupe de Weyl affine. Sa nature est encodée dans la présentation de Bernstein et contient d’importantes informations sur les représentations de l’algèbre. Si on considère des catégorifications de cette algèbre\, par exemple la catégorie diagrammatique\, cette sous-algèbre correspond à une classe de complexes dans la catégorie homotopique appelés faisceaux de Wakimoto\, que l’on peut voir comme des complexes de Rouquier. \nDans cet exposé j’introduirai la catégorie de Hecke affine\, et les objets mentionnés ci-dessus. Je présenterai ensuite des résultats de réduction des complexes de Rouquier et d’étude des groupes d’extension entre faisceaux de Wakimoto en type A_1 affine.
URL:https://lmv.math.cnrs.fr/evenenement/leonardo-maltoni-lmv/
LOCATION:Bâtiment Fermat\, salle 4205
CATEGORIES:Séminaire AG
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20221117T140000
DTEND;TZID=Europe/Paris:20221117T150000
DTSTAMP:20260525T090715
CREATED:20220928T120546Z
LAST-MODIFIED:20221118T100408Z
UID:10836-1668693600-1668697200@lmv.math.cnrs.fr
SUMMARY:EDP : Belhassen Dehman (Univ. Tunis El Manar) : Boundary sidewise observability of the wave equation
DESCRIPTION:In this paper we consider a wave equation on a bounded domain Ω of Rn\, with non homogeneous boundary Dirichlet data g supported on a part of the boundary\, and we prove an observability estimate of this data from the rest of the boundary. This result is obtained under a geometrical condition on the part of the boundary supporting g to be compared to the so-called Geometric Control Condition of Bardos-Lebeau-Rauch\, and on a pseudo-differential condition on g. The proof relies on microlocal arguments and is essentially based on properties of microlocal defect measures.
URL:https://lmv.math.cnrs.fr/evenenement/edp-belhassen-dehman-univ-tunis-el-manar-boundary-sidewise-observability-of-the-wave-equation/
LOCATION:Bâtiment Fermat\, salle 4205
CATEGORIES:Séminaire EDP
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20221122T140000
DTEND;TZID=Europe/Paris:20221122T150000
DTSTAMP:20260525T090715
CREATED:20220915T151914Z
LAST-MODIFIED:20230509T133306Z
UID:10751-1669125600-1669129200@lmv.math.cnrs.fr
SUMMARY:AG : Baptiste Rognerud (IMJ-PRG) : Ensembles ordonnés Calabi-Yau fractionnaires\, exemples et conjectures.
DESCRIPTION:L’algèbre d’incidence d’un ensemble ordonné fini sur un corps est de dimension globale finie\, bornée par la taille de l’ensemble ordonné\, donc sa catégorie dérivée bornée possède ce qu’on appelle un `foncteur de Serre’. On dit qu’un ensemble ordonné est « Calabi-Yau fractionnaire » si une certain puissance de ce foncteur de Serre est isomorphe à un foncteur de décalage. \nL’exemple\, non trivial\, le plus simple est celui de l’ordre total et plus généralement les orientations des diagrammes de Dynkin de types A\,D et E en fournissent d’autres. On verra qu’il existe des exemples plus compliqués venant de la combinatoire classique et de la théorie des représentations.
URL:https://lmv.math.cnrs.fr/evenenement/ag-baptiste-rognerud-imj-prg/
LOCATION:Bâtiment Fermat\, salle 4205
CATEGORIES:Séminaire AG
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20221124T110000
DTEND;TZID=Europe/Paris:20221124T120000
DTSTAMP:20260525T090715
CREATED:20221116T081232Z
LAST-MODIFIED:20230509T133324Z
UID:11066-1669287600-1669291200@lmv.math.cnrs.fr
SUMMARY:CRYPTO : Augustin Bariant (INRIA) : Algebraic Attacks against Some Arithmetization-Oriented Symmetric Cryptographic Algorithms
DESCRIPTION:In some recent advanced protocols\, like Zero-Knowledge Proofs (allowing a prover to convince a verifier that he knows a secret without revealing it)\, or Multi Party Computation\, algorithms do not process bit-oriented information\, but rather elements of big finite fields Z/qZ. In that regard\, the only operations allowed in such algorithms are additions and multiplications in the field. These protocols therefore require cryptographic algorithms that are not optimized for usual bit-oriented platforms (desktop computers\, servers\, microcontrollers\, RFID tags…)\, but rather for their short implementation in Z/qZ. These are called arithmetization-oriented cryptographic algorithms. \nSince 2016\, several arithmetization-oriented algorithms have been presented. Their security highly depends on the complexity of polynomial root-finding and Groebner basis algorithms\, which define a special class of attacks: algebraic attacks. In 2021\, the Ethereum Foundation launched a series of challenges on this new class of ciphers\, aiming at better understanding the threat of algebraic attacks. We took that opportunity to perform a thorough study of univariate and multivariate polynomial solving algorithms in big fields. \nIn this talk\, we present an overview of existing algebraic attacks and analysis\, along with new theoretical and experimental results on several ciphers.
URL:https://lmv.math.cnrs.fr/evenenement/crypto-augustin-bariant-inria-algebraic-attacks-against-some-arithmetization-oriented-symmetric-cryptographic-algorithms/
LOCATION:Bâtiment Fermat\, salle 4205
CATEGORIES:Séminaire CRYPTO
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20221129T103000
DTEND;TZID=Europe/Paris:20221129T113000
DTSTAMP:20260525T090715
CREATED:20220901T094708Z
LAST-MODIFIED:20221201T153810Z
UID:10687-1669717800-1669721400@lmv.math.cnrs.fr
SUMMARY:Klara Nosan (IRIF\, Université Paris-Cité)\, On the membership problem for hypergeometric sequences with rational parameters
DESCRIPTION:Plus d’information sur la page web du séminaire : http://divizio.joomla.com/sem-diff
URL:https://lmv.math.cnrs.fr/evenenement/journee-du-seminaire-differentiel-2/
CATEGORIES:Séminaire AG,Séminaire différentiel
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20221129T140000
DTEND;TZID=Europe/Paris:20221129T150000
DTSTAMP:20260525T090715
CREATED:20221101T142502Z
LAST-MODIFIED:20221201T153854Z
UID:11028-1669730400-1669734000@lmv.math.cnrs.fr
SUMMARY:Julien Roques (ICJ\, Université Lyon 1)\, Around Mahler equations
DESCRIPTION:plus d’informations ici : http://divizio.joomla.com/sem-diff
URL:https://lmv.math.cnrs.fr/evenenement/julien-roques-icj-universite-lyon-1-around-mahler-equations/
CATEGORIES:Séminaire AG,Séminaire différentiel
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20221129T153000
DTEND;TZID=Europe/Paris:20221129T163000
DTSTAMP:20260525T090715
CREATED:20221101T142816Z
LAST-MODIFIED:20221201T153836Z
UID:11033-1669735800-1669739400@lmv.math.cnrs.fr
SUMMARY:Éric Delaygue (ICJ\, Université Lyon 1)\, On Abel's problem and Gauss congruences
DESCRIPTION:Plus d’information ici : http://divizio.joomla.com/sem-diff
URL:https://lmv.math.cnrs.fr/evenenement/eric-delaygue-icj-universite-lyon-1-on-abels-problem-and-gauss-congruences/
CATEGORIES:Séminaire AG,Séminaire différentiel
END:VEVENT
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