University of Ulsan
When
2 – 3 p.m., Dec. 2, 2025
Where
Title: CM K3 surfaces and supersingular reduction
Abstract: A complex K3 surface has a complex multiplication if the Hodge structure of the trascendental part has an abelian Hodge group. A K3 surface over a field of positive characteristic is supersingular if the Picard number 22. Kazuhiro Ito had a criterion to determine at which place, the reduction of a CM K3 surface is supersingular. In this talk, we will see all but finitely many supersingular reductions of a CM K3 surface is of special type. This result can be regarded as a kind of counter part of that every K3 surface of finite height over a finite field has a CM lifting.