26/10/2017, 14:30 — 15:30 — Sala P4.35, Pavilhão de Matemática
Geoffroy Horel, Université Paris XIII
Mixed Hodge structure, Galois actions and formality
Given a dg-algebra or any algebraic structure in chain complexes, one may ask if it is quasi-isomorphic to its homology equipped with the zero differential. This property is called formality and has important consequences in algebraic topology. For example it forces the collapse of certain spectral sequences. In this talk I will explain how mixed Hodge structures can be used to prove formality when working with rational coefficients. I will also explain work in progress using Galois actions as a replacement for mixed Hodge structures in the case of torsion coefficients. This is joint work with Joana Cirici.
