Next Meeting: October 24, 2025
Department of Mathematics / CMUC Universidade de Coimbra
10:30 Sebastián Daza (Universidade de Coimbra) - Deformations of Lie algebroid morphisms
11:40 Ricardo Campos (CNRS - University of Toulouse) - From Lie algebroids to curved Lie algebras
12:40 Lunch
14:30 Carlos Florentino (Universidade de Lisboa) - Fano polygon spaces
15:30 Coffee Break
16:00 Lennart Obster (Universidade de Coimbra) - Representation theory for Lie groupoids revisited: VB-groupoids, representations up to homotopy, and fat extensions
Abstracts
Sebastián Daza - Deformations of Lie algebroid morphisms
Abstract:
Ricardo Campos - From Lie algebroids to curved Lie algebras
Abstract: A classical slogan from the 1970s says that infinitesimal deformation problems are controlled by differential graded Lie algebras. Recent work suggests that one can also formulate this principle for “unpointed” deformation problems.
Two different generalizations of dg Lie algebras capture this idea of unpointedness: On one hand, one can allow them to live over a more general manifold, leading to (dg) Lie algebroids. On the other hand, we can introduce a differential squaring to a non-zero “curvature,” giving curved Lie algebras. In this talk I will explain these notions and show that they are closely related.
The results are based on arXiv:2103.10728, joint work with Damien Calaque and Joost Nuiten.
Carlos Florentino - Fano polygon spaces
Abstract:
Lennart Obster (Universidade de Coimbra) - Representation theory for Lie groupoids revisited: VB-groupoids, representations up to homotopy, and fat extensions
Abstract: As for Lie groups, Lie groupoids come with an adjoint representation. Its definition is a bit more subtle: the adjoint representation can be “singular” in a precise sense. A derived viewpoint lead to the adjoint representation being introduced as a 2-term representation up to homotopy (ruth). Later, it was realised that vector bundles over groupoids (VB-groupoids) are a type of double structure that is equivalent to 2-term ruths.
In joint work with João Nuno Mestre and Luca Vitagliano, while studying multiplicative tensors on groupoids, we realised there is yet another point of view.
In this talk, a category of “fat extensions” will be introduced. This category is equivalent to the category of VB-groupoids (resp. 2-term ruths). The emphasis will be on explaining aspects of the various correspondences that we find enlightening for the study of multiplicative tensors. If time permits, we will also briefly introduce the infinitesimal analogue (for Lie algebroids) of the discussion.
Organizers:
Ana Cristina Ferreira (CMAT, Universidade do Minho) ✉️
João Nuno Mestre (CMUC, Universidade de Coimbra) ✉️
Giosuè Muratore (CEMS.UL, Universidade de Lisboa) ✉️
André Oliveira (CMUP, Universidade do Porto) ✉️
Gonçalo Oliveira (CAMGSD, Instituto Superior Técnico, Universidade de Lisboa) ✉️
The idea and composition of the above logo of these GEMS are due to Pedro Silva.
Another webpage for the GEMS may be found here.