The Mudcat Café TM
Thread #59418 Message #3928213
Posted By: Rapparee
31-May-18 - 08:47 AM
Thread Name: BS: The Mother of all BS threads
Subject: RE: BS: The Mother of all BS threads
Oh, yeah. Donuel, remember that in two complex dimensions, the K3 surfaces furnish the only compact simply connected Calabi–Yau manifolds. Non simply-connected examples are given by abelian surfaces. Enriques surfaces and hyperelliptic surfaces have first Chern class that vanishes as an element of the real cohomology group, but not as an element of the integral cohomology group, so Yau's theorem about the existence of a Ricci-flat metric still applies to them but they are sometimes not considered to be Calabi–Yau manifolds.