BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Laboratoire de Mathématiques de Versailles - ECPv6.3.5//NONSGML v1.0//EN CALSCALE:GREGORIAN METHOD:PUBLISH X-WR-CALNAME:Laboratoire de Mathématiques de Versailles X-ORIGINAL-URL:https://lmv.math.cnrs.fr X-WR-CALDESC:évènements pour Laboratoire de Mathématiques de Versailles 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:20220327T010000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET DTSTART:20221030T010000 END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20221108T140000 DTEND;TZID=Europe/Paris:20221108T150000 DTSTAMP:20240328T173735 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:20240328T173735 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:20240328T173735 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:20240328T173735 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:20240328T173735 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:20240328T173735 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:20240328T173735 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:20240328T173735 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 END:VCALENDAR