Every rational Hodge isometry between two K3 surfaces is algebraic

Nikolay Buskin

We prove that given any rational Hodge isometry $\psi :H^2(S_1,\mathbb{Q})\to H^2(S_2,\mathbb{Q})$ between any two Kähler $K3$ surfaces $S_1$ and $S_2$ the cohomology class of…