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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:20150329T010000
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TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:20151025T010000
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BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20151001T140000
DTEND;TZID=Europe/Paris:20151001T140000
DTSTAMP:20260416T021252
CREATED:20151001T120000Z
LAST-MODIFIED:20211104T100012Z
UID:8236-1443708000-1443708000@www.math.ens.psl.eu
SUMMARY:Resolution of singularities by p-alterations
DESCRIPTION:de Jong proved that any variety X can be desingularized by an alteration f:X’–>X\, i.e. a proper surjective generically finite morphism. This was strengthened by Gabber as follows: f can be chosen of degree prime to a fixed prime l invertible on X.In this talk\, I’ll tell about the most recent progress on the subject: if X is of finite type over a quasi-excellent threefold then one can desingularize X by an alteration whose degree is only divisible by primes non-invertible on X. We will also discuss finer results that deal with divisors and desingularize morphisms in the sense of semistable reduction.
URL:https://www.math.ens.psl.eu/evenement/resolution-of-singularities-by-p-alterations/
CATEGORIES:Séminaire de géométrie algébrique
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20151008T140000
DTEND;TZID=Europe/Paris:20151008T150000
DTSTAMP:20260416T021252
CREATED:20151008T120000Z
LAST-MODIFIED:20211104T100212Z
UID:8238-1444312800-1444316400@www.math.ens.psl.eu
SUMMARY:The Base Point Free Theorem in positive characteristic
DESCRIPTION:In positive characteristic the Base Point Free Theorem is still an open problem. In a joint work with Jakub Witaszek and Yusuke Nakamura\, we proved the Base Point Free theorem for varieties of dimension three with log canonical singularities defined over the algebraic closure of a finite field. I will give an introduction to the problem and describe the tools that we used in the proof.
URL:https://www.math.ens.psl.eu/evenement/the-base-point-free-theorem-in-positive-characteristic/
CATEGORIES:Séminaire de géométrie algébrique
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20151009T150000
DTEND;TZID=Europe/Paris:20151009T160000
DTSTAMP:20260416T021252
CREATED:20151009T130000Z
LAST-MODIFIED:20211104T100346Z
UID:8244-1444402800-1444406400@www.math.ens.psl.eu
SUMMARY:Approximation forte pour les G-variétés contenant une orbite ouverte.
DESCRIPTION:(Travail en collaboration avec Fei Xu). L’approximation forte avec l’obstruction de Brauer-Manin est définie par Colliot-Thélène et Xu. C’est une méthode pour étudier le principe local-global pour les points entiers. Dans cet exposé\, soient k un corps de nombres\, G un groupe linéaire sur k\, X une G-variété lisse géométriquement intègre et U une G-orbite ouverte de X. Je parlerai de notre résultat dans le cas où U est isomorphe à G\, et j’expliquerai sa démonstration. Ensuite\, je parlerai de notre programme dans le cas où U est isomorphe à G/H\, avec H connexe.
URL:https://www.math.ens.psl.eu/evenement/approximation-forte-pour-les-g-varietes-contenant-une-orbite-ouverte/
LOCATION:ENS Salle W
CATEGORIES:Variétés rationnelles
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20151009T163000
DTEND;TZID=Europe/Paris:20151009T173000
DTSTAMP:20260416T021252
CREATED:20151009T143000Z
LAST-MODIFIED:20211104T100346Z
UID:8245-1444408200-1444411800@www.math.ens.psl.eu
SUMMARY:Failures of weak approximation in families.
DESCRIPTION:Given a family of varieties over a number field\, we investigate the variation of the Brauer-Manin obstruction within the family. We give sufficient conditions on a family of varieties over P^n for 100% of the family to have a Brauer-Manin obstruction to weak approximation (this is joint work with Tim Browning and Dan Loughran).
URL:https://www.math.ens.psl.eu/evenement/failures-of-weak-approximation-in-families/
LOCATION:ENS Salle W
CATEGORIES:Variétés rationnelles
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20151015T140000
DTEND;TZID=Europe/Paris:20151015T150000
DTSTAMP:20260416T021252
CREATED:20151015T120000Z
LAST-MODIFIED:20211104T100211Z
UID:8237-1444917600-1444921200@www.math.ens.psl.eu
SUMMARY:Semisimplicité de la cohomologie quantique de certaines variétés de Fano
DESCRIPTION:Je donnerai une condition suffisante pour que l’anneau de cohomologie quantique soit semisimple et expliquerai comment l’appliquer à certaines variétés de Fano ayant un grand indice. Je considérerai tout particulièrement l’exemple des sections linéaires de grassmanniennes de droites.
URL:https://www.math.ens.psl.eu/evenement/semisimplicite-de-la-cohomologie-quantique-de-certaines-varietes-de-fano/
CATEGORIES:Séminaire de géométrie algébrique
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20151015T151500
DTEND;TZID=Europe/Paris:20151015T161500
DTSTAMP:20260416T021252
CREATED:20151015T131500Z
LAST-MODIFIED:20211104T100212Z
UID:8239-1444922100-1444925700@www.math.ens.psl.eu
SUMMARY:Compter des courbes ouvertes via des courbes fermées
DESCRIPTION:
URL:https://www.math.ens.psl.eu/evenement/compter-des-courbes-ouvertes-via-des-courbes-fermees/
CATEGORIES:Séminaire de géométrie algébrique
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20151022T140000
DTEND;TZID=Europe/Paris:20151022T150000
DTSTAMP:20260416T021252
CREATED:20151022T120000Z
LAST-MODIFIED:20211104T100212Z
UID:8240-1445522400-1445526000@www.math.ens.psl.eu
SUMMARY:Quasimap invariants\, Gromov-Witten invariants\, and Mirror Symmetry
DESCRIPTION:
URL:https://www.math.ens.psl.eu/evenement/quasimap-invariants-gromov-witten-invariants-and-mirror-symmetry/
CATEGORIES:Séminaire de géométrie algébrique
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20151022T151500
DTEND;TZID=Europe/Paris:20151022T161500
DTSTAMP:20260416T021252
CREATED:20151022T131500Z
LAST-MODIFIED:20211104T100213Z
UID:8241-1445526900-1445530500@www.math.ens.psl.eu
SUMMARY:Complete twisted cubics
DESCRIPTION:
URL:https://www.math.ens.psl.eu/evenement/complete-twisted-cubics/
CATEGORIES:Séminaire de géométrie algébrique
END:VEVENT
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