Sumários

Holonomy - V

29 Maio 2024, 15:30 Giordano Cotti


In this last lecture, we addressed the study of Riemannian holonomies. We formulated and discussed the remarkable "de Rham Decomposition Theorem". We concluded by presenting Berger's list of possible Riemannian holonomies for a simply-connected manifold that is irreducible and not locally a symmetric space. The lecture introduced the notions of Kähler, Calabi-Yau, hyper-Kähler, quaternion Kähler, and Einstein manifolds. Finally, we mentioned Dominic Joyce's recent works on the existence of G2 and Spin(7) manifolds.

Holonomy - IV

28 Maio 2024, 10:00 Giordano Cotti


In this lecture, we focused on connections defined on the tangent bundle of a manifold. We introduced the notion of torsion, and proved the first and second Bianchi identities. Additionally, we introduced the concept of connections compatible with a metric, and formulated and proved the fundamental theorem regarding the existence and uniqueness of the Levi-Civita connection.

Holonomy - III

22 Maio 2024, 15:30 Giordano Cotti


We continued and completed the proof of the Ambrose-Singer-Nijenhuis Theorem. As a deep result, we recalled Yamabe's theorem: an arcwise connected subgroup of a Lie group is a Lie subgroup.

Holonomy - II

21 Maio 2024, 10:00 Giordano Cotti


In this lecture, we introduced the holonomy group of a connection at a point, as well as the restricted holonomy group. We formulated and began to prove the Ambrose-Singer-Nijenhuis Theorem: the restricted holonomy group is a connected Lie group with a Lie algebra determined by the curvature.

Holonomy - I

15 Maio 2024, 15:30 Giordano Cotti


In this lecture, we addressed the following problem: given two homotopic curves c1 and c2, what is the difference in the parallel transport along these curves? We showed that the curvature is responsible for this difference. 


In particular, we showed that if the connection is flat, then the parallel transport defines a functional on homotopy classes of curves. 

Finally, we gave a complete proof of an already mentioned fact: on a simply-connected manifold, a vector bundle is flat if and only if it is trivial.