{"id":338,"date":"2026-06-08T10:14:03","date_gmt":"2026-06-08T08:14:03","guid":{"rendered":"https:\/\/www.imj-prg.fr\/tga\/?p=338"},"modified":"2026-06-15T13:26:39","modified_gmt":"2026-06-15T11:26:39","slug":"demi-journee-des-doctorant-e-s-de-lequipe-tga-lundi-15-juin-2026","status":"publish","type":"post","link":"https:\/\/www.imj-prg.fr\/tga\/demi-journee-des-doctorant-e-s-de-lequipe-tga-lundi-15-juin-2026\/","title":{"rendered":"Demi-journ\u00e9e des doctorant.e.s de l&rsquo;\u00e9quipe TGA : lundi 15 juin 2026"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Comme chaque ann\u00e9e, une demi-journ\u00e9e d&rsquo;expos\u00e9s est organis\u00e9e pour permettre aux doctorant.e.s de l&rsquo;\u00e9quipe de pr\u00e9senter leurs travaux. Cette ann\u00e9e, nous aurons le plaisir d&rsquo;\u00e9couter des expos\u00e9s de :<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Jordan Levin : Manifold Structures and Cohomology<br>In differential geometry, there is the fundamental problem of classifying smooth manifolds up to diffeomorphism. Similarly, in algebraic topology, there is the question of classifying spaces up to homotopy equivalence. Both of these classification problems are notoriously difficult in general. Remarkably, if we fix a homotopy type together with suitable auxiliary data, the problem of classifying compatible manifolds admits an algebraic description through the machinery of Surgery Theory. Roughly speaking, the relevant algebraic invariants arise as the homotopy groups of generalized cohomology theories called Algebraic L-theory. Though much of this theory was developed in the last century, my work concerns modern refinements arising from new perspectives in higher algebra and stable homotopy theory.<\/li>\n\n\n\n<li>Michele Tamagnone : The Decomposition Theorem for the Beauville-Mukai system<br>Ng\u00f4\u2019s refinement of the BBDG decomposition theorem is a strong tool for the study of the cohomology of Lagrangian fibrations: it allows to describe the cohomology of the total space in terms of certain strings identified by local systems on the base.<br>We will see this at work for the Beauville-Mukai system, a deformation of the Hitchin system parametrizing sheaves on a K3 surface. Ng\u00f4\u2019s theorem will reduce the proof of the full support property for this system to the study of the irreducible components of the compactified Jacobian of a non-reduced curve with non-smooth reduction, an argument not deeply explored in the literature.<\/li>\n\n\n\n<li>Tianyang Wang : Obstruction de Brauer-Manin transcendante pour les espaces homog\u00e8nes<br>L&rsquo;obstruction de Brauer-Manin est un outil arithm\u00e9tique fondamental introduit pour expliquer les d\u00e9fauts au principe de Hasse et \u00e0 l&rsquo;approximation faible sur les vari\u00e9t\u00e9s alg\u00e9briques. Son \u00e9tude sur les espaces homog\u00e8nes s&rsquo;est historiquement concentr\u00e9e sur la partie alg\u00e9brique du groupe de Brauer, aboutissant notamment aux r\u00e9sultats de Borovoi en 1996 pour les stabilisateurs ab\u00e9liens ou connexes.<br>Durant cette pr\u00e9sentation, je rappellerai d&rsquo;abord un exemple de d\u00e9faut au principe de Hasse et l&rsquo;\u00e9mergence de l\u2019obstruction de Brauer-Manin avant de pr\u00e9senter la divergence de nature entre les obstructions alg\u00e9briques et transcendantes. J\u2019illustrerai ensuite la n\u00e9cessit\u00e9 de cette composante transcendante en d\u00e9taillant un contre-exemple explicite et r\u00e9cent \u00e0 l&rsquo;approximation faible sur un espace homog\u00e8ne.<\/li>\n\n\n\n<li>Ronghan Yuan : Skein Algebras at Roots of Unity<br>Skein algebras can be thought of as noncommutative versions of the coordinate rings of SL2C-character varieties. Bonahon\u2013Wong and Frohman\u2013Kania-Bartoszynska\u2013L\u00ea identified the center of these algebras and showed that it is isomorphic to the coordinate ring of the character variety. They also proved that, after localizing the center appropriately, the skein algebra is Azumaya.<br>Later, Ganev\u2013Jordan\u2013Safronov and also Detcherry\u2013Santharoubane showed that the skein algebra is Azumaya over the smooth locus of the character variety. In this short talk, I will discuss how to prove that this Azumaya algebra is nontrivial, using its Brauer class as a cohomological invariant.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Les expos\u00e9s commenceront \u00e0 14h30 et se termineront \u00e0 17h30. Ils seront suivis d&rsquo;un buffet convivial.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Comme chaque ann\u00e9e, une demi-journ\u00e9e d&rsquo;expos\u00e9s est organis\u00e9e pour permettre aux doctorant.e.s de l&rsquo;\u00e9quipe de pr\u00e9senter leurs travaux. Cette ann\u00e9e, nous aurons le plaisir d&rsquo;\u00e9couter des expos\u00e9s de : Les expos\u00e9s commenceront \u00e0 14h30 et se termineront \u00e0 17h30. Ils seront suivis d&rsquo;un buffet convivial.<\/p>\n","protected":false},"author":41,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-338","post","type-post","status-publish","format-standard","hentry","category-non-classe"],"_links":{"self":[{"href":"https:\/\/www.imj-prg.fr\/tga\/wp-json\/wp\/v2\/posts\/338","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.imj-prg.fr\/tga\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.imj-prg.fr\/tga\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.imj-prg.fr\/tga\/wp-json\/wp\/v2\/users\/41"}],"replies":[{"embeddable":true,"href":"https:\/\/www.imj-prg.fr\/tga\/wp-json\/wp\/v2\/comments?post=338"}],"version-history":[{"count":9,"href":"https:\/\/www.imj-prg.fr\/tga\/wp-json\/wp\/v2\/posts\/338\/revisions"}],"predecessor-version":[{"id":347,"href":"https:\/\/www.imj-prg.fr\/tga\/wp-json\/wp\/v2\/posts\/338\/revisions\/347"}],"wp:attachment":[{"href":"https:\/\/www.imj-prg.fr\/tga\/wp-json\/wp\/v2\/media?parent=338"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.imj-prg.fr\/tga\/wp-json\/wp\/v2\/categories?post=338"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.imj-prg.fr\/tga\/wp-json\/wp\/v2\/tags?post=338"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}