K\"ahler-Ricci Shrinkers and Ancient Solutions with Nonnegative Orthogonal Bisectional Curvature

Abstract

In this paper we prove classification results for gradient shrinking Ricci solitons under two invariant conditions, namely nonnegative orthogonal bisectional curvature and weakly PIC1, without any curvature bound. New results on ancient solutions for the Ricci and K\"ahler-Ricci flow are also obtained. The main new feature is that no curvature upper bound is assumed.