4. Local Systems and Perverse Sheaves

Abstract

In this chapter we introduce the results on local systems and perverse sheaves which will be used in the following next chapters.

Throughout this chapter, the letter X denotes an algebraic variety over $\overline{\mathbb{F}}_q$. As in the previous chapter, we denote by $\ell$ a prime not equal to p and by $\overline{\mathbb{Q}}_{\ell}$ an algebraic closure of $\mathbb{Q}_{\ell}$. In the following, the finite extensions of $\mathbb{Q}_{\ell}$ considered are in $\overline{\mathbb{Q}}_{\ell}$.