Assume $ \pi:Y \rightarrow X$ is an unramified double cover of smooth projective varieties with Galois group $ G:=<\iota>$ , $ \iota^2=id_Y$ and $ X=Y/G$ , so $ G$ acts freely on $ Y$ (everything over $ \mathbb{C}$ ). We have furthermore an additional sheaf of rings or algebras $ R_X$ on $ X$ ,Read more