Gravitational instantons, rational surfaces, and K3 surfaces
アブストラクト
I will describe some examples of complete non-compact Ricci-flat metrics in dimension 4, which are called "gravitational instantons." In many cases, these can be compactified complex analytically to rational surfaces. I will also discuss how these gravitational instantons can arise from sequences of degenerating Ricci-flat metrics on the compact K3 surface, through a process called "bubbling".