I need the theorems that prove that Nisnevich cohomology can be computed by the Cech complex similar to what happens in the étale topology. I know this has to be true since (More …

Given a topological space $X$, we consider the following category $\mathsf{CW}_{X\to}$. The objects are finite CW complexes $Y$ equipped with a continuous map $X\to Y$. The morph …

Are there any good references/explanations for understanding the "contracted product" (as Brylinski calls it) of a gerbe with abelian band? I am finding it difficult, using Brylisn …

Possible Duplicate: Example Wanted: When Does Cech Cohomology Fail to be the same as Derived Functor Cohomology? Is there a simple example of a topological space $X$ with …

Hi, The following result seems to be well known, but I can't come up with a proof. Suppose that $C$ is a topos and that $F\to G$ is an effective epimorphism in $C$. If $P$ is any …