Karol Janowicz

Bounded functor cohomology and comparison theorem

Let $k$ be a finite field. We consider the category of all functors $\mathcal{F}_n$ from the category of $k$-vector spaces of dimension $\leq n$ into the category of all $k$-vector spaces. We compare its derived category to the derived category of representations of the general linear group $GL_n(k)$ using the extension by zero functor procedure. We upgrade the well-known recollement of abelian categories into the recollement of the corresponding derived categories. Then we obtain some translations of the cohomology the general linear group over finite field. We also compare $\mathcal{F}_n$ with the category of polynomial functors $\mathcal{P}_{d,n}$, giving further reformulations over big finite fields.