An Overview on Closed G2-Structures

Explore an in-depth overview of closed G_2-structures on 7-manifolds in this 51-minute lecture by Anna Fino from Florida International University. Delve into the definition of closed G_2-structures as closed positive 3-forms and their significance in potential methods for obtaining holonomy G_2-metrics. Trace the history of G_2 holonomy from Marcel Berger's 1955 classification theorem to the challenges in constructing holonomy G_2-metrics. Examine the Hitchin flow equations as a method for deriving local metrics with holonomy in G_2 from 6-manifolds. Investigate the restrictive nature of the closed condition for G_2-structures and review known examples of compact 7-manifolds admitting closed G_2-structures. Discuss recent findings on exact G_2-structures and analyze the behavior of the Laplacian G_2-flow under specific metric conditions, interpreting it as the gradient flow of the Hitchin volume functional in compact settings.