Buongiorno, Ricordo a tutti gli interessati che il prossimo seminario di geometria sarà tenuto da Andrea Sambusetti e si terrà domani Martedì 3 Dicembre alle ore 14:30 presso l'aula Riunioni. Per gli interessati ad andare a pranzo con lo speaker, l'appuntamento è in atrio alle 13:00. Allego titolo e abstract: Titolo: Two rigidity theorems for CAT(0)-spaces (via convergence theory) Abstact: I will present two rigidity results about CAT(0)-spaces. The first one concerns the isolation of flat spaces among (geodesically complete) CAT(0)-spaces admitting cocompact lattices, provided that the codiameter is uniformily bounded. The second one is an entropy-pinching theorem saying that if a uniformly packed and uniformly cocompact CAT(0)-space has entropy small enough, then it is flat. Both results stem from a careful study of the theory of (equivariant) Gromov-Hausdorff convergence of lattices of CAT(0)-spaces and of their possible degenerations, whose main lines I will try to explain. A presto, Carlo e Filippo