Theorem 64.27.4 (Deligne, Weil II). For a sheaf $\mathcal{F}_\rho $ with $\rho $ satisfying the conclusions of the conjecture above then the eigenvalues of $\pi _ X^*$ on $H_ c^ i(X_{\overline{k}}, \mathcal{F}_{\rho })$ are algebraic numbers $\alpha $ with absolute values
\[ |\alpha |=q^{w/2}, \text{ for }w\in \mathbf{Z},\ w\leq i \]
Moreover, if $X$ smooth and proj. then $w = i$.
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