Number of triple points on complete intersection Calabi-Yau threefolds

Abstract

We discuss bounds for the number of ordinary triple points on complete intersection Calabi-Yau threefolds in projective spaces and for Calabi-Yau threefolds in weighted projective spaces. In particular, we show that in P5 the intersection of a quadric and a quartic cannot have more than 10 ordinary triple points. We provide examples of complete intersection Calabi-Yau threefolds with multiple triple points. We obtain the exact bound for a sextic hypersurface in P[1 : 1 : 1 : 1 : 2], which is 10. We also discuss Calabi-Yau threefolds that cannot admit triple points.