Speaker
Jeff Viaclovsky, UC Irvine
Abstract
A gravitational instanton is a complete non-flat hyperkahler metric in dimension four whose curvature tensor is square-integrable. Thanks to the work of many authors, these have recently been completely classified. In the non-compact case, they must be of type ALE, ALF, ALG, ALG^*, ALH, or ALH^*, and the hyperkahler structure is given by various known constructions. In this talk, I will discuss some aspects of this classification.