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arXiv · 2207.06033

Polynomial equations modulo prime numbers

Arnaud Bodin·Pierre Dèbes·Salah Najib
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Abstract

We consider polynomial equations, or systems of polynomial equations, with integer coefficients, modulo prime numbers $p$. We offer an elementary approach based on a counting method. The outcome is a weak form of the Lang-Weil lower bound for the number of solutions modulo $p$, only differing from Lang-Weil by an asymptotic $p^\epsilon$ multiplicative factor. Our second contribution is a reduction lemma to the case of a single equation which we use to extend our results to systems of equations. We show further how to use this reduction to prove the full Lang-Weil estimate for varieties, assuming it for hypersurfaces, in a version using a variant of the classical degree in the error term.

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Arnaud Bodin, Pierre Dèbes, Salah Najib. 2022-07-13. Polynomial equations modulo prime numbers. https://arxiv.org/abs/2207.06033

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