Hi,

Consider the zeta function of a definable set over a finite field. More precisely, let $X$ be a definable subset of $F^n$ where $F$ is a finite field of characteristic $p$, then $$ Z_X(t)= \exp \sum_{i=1}^ \infty \frac{N_i(X)}{i} t^i, $$ where $N_i(X)= card \{ (a_1,\dots,a_n) \in F_i^n| F_i \models \varphi[a_1,\dots,a_n]\}$ with $F_i$ is the unique extension of $F$ of degree $i$ and $\varphi$ is the formula defining $X$.

My question is:

Does the Riemann hypothesis for $Z_X(t)$ hold, i.e. if we make the change of variables $t=q^{-s}$ does it follow that all zeroes of $Z_X(q^{-s})$ lie on the line $Re(s)=1/2$?

Thank you