Let X be a projective variety over a finite field
with function field K(X). Let Y be a projective variety
over K(X). We may associate to this a height zeta
function. In this talk, we will recall some facts
about these functions and provide some new results
and research directions.
I will give an overview of some l-adic methods used
to prove estimates for exponential sums, and use a combination of these methods to prove a purity theorem
for exponential sums on A^n.