In algebraic topology and algebraic geometry, Leray's theorem (so named after Jean Leray) relates abstract sheaf cohomology with Čech cohomology. Let be a sheaf on a topological space and an open cover of If is acyclic on every finite intersection of elements of , then where is the -th Čech cohomology group of with respect to the open cover References Bonavero, Laurent. Cohomology of Line Bundles on Toric Varieties, Vanishing Theorems. Lectures 16-17 from "Summer School 2000: Geometry of Toric Varieties." Sheaf theory Theorems in algebraic geometry Theorems in algebraic topology