Séminaires : Séminaire d'Algèbre

Equipe(s) : gr,
Responsables :J. Alev, D. Hernandez, B. Keller, Th. Levasseur, et S. Morier-Genoud.
Email des responsables : Jacques Alev <jacques.alev@univ-reims.fr>, David Hernandez <david.hernandez@imj-prg.fr>, Bernhard Keller <bernhard.keller@imj-prg.fr>, Thierry Levasseur <Thierry.Levasseur@univ-brest.fr>, Sophie Morier-Genoud <sophie.morier-genoud@imj-prg.fr>
Salle : format hybride, IHP salle 01 et/ou à distance (Zoom). Info sur https://researchseminars.org/seminar/paris-algebra-seminar
Adresse :IHP

Le séminaire est prévu en présence à l'IHP et à distance. Pour les liens et mots de passe, merci de contacter l'un des organisateurs ou de souscrire à la liste de diffusion https://listes.math.cnrs.fr/wws/info/paris-algebra-seminar. L'information nécessaire sera envoyée par courrier électronique peu avant chaque exposé. Les notes et transparents sont disponibles ici.


Since March 23, 2020, the seminar has been taking place remotely. For the links and passwords, please contact one of the organizers or

subscribe to the mailing list at https://listes.math.cnrs.fr/wws/info/paris-algebra-seminar. The connexion information will be emailed shortly before each talk. Slides and notes are available here.


Orateur(s) Florian Naef - ,
Titre The (non-)homotopy invariance of the string coproduct
Horaire14:00 à 15:00

A Calabi-Yau structure on a smooth algebra allows one to identify Hochschild homology with Hochschild cohomology. With this identification Hochschild homology acquires an additional Gerstenhaber algebra structure. One way to formulate the amount of structure one has on Hochschild homology is to encode it into a 2d TFT. This explains some of the string topology operations on the free loop space of a manifold, but not the string coproduct. If the algebra has additional structure (trivialization of its Hattori-Stalling Euler characteristic) one obtains an extra secondary operation on Hochschild homology, which recovers the string coproduct. Finally, in the free loop space setting, this additional structure can either be recovered from intersection theory of the manifold or from its underlying simple homotopy type, thus relating the two. Using this last relation one can express the difference between the string coproduct of two homotopic but not necessarily homeomorphic manifolds in terms of Whitehead torsion.
This is joint work with Pavel Safronov

Salleformat hybride, IHP salle 01 et/ou à distance (Zoom). Info sur https://researchseminars.org/seminar/paris-algebra-seminar