Maximum number of points on intersection of a cubic surface and a non-degenerate Hermitian surface

Peter Beelen; Mrinmoy Datta

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arXiv · 1802.06681

Maximum number of points on intersection of a cubic surface and a non-degenerate Hermitian surface

Peter Beelen·Mrinmoy Datta

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Abstract

In 1991 S{\o}rensen proposed a conjecture for the maximum number of points on the intersection of a surface of degree $d$ and a non-degenerate Hermitian surface in $\PP^3(\Fqt)$. The conjecture was proven to be true by Edoukou in the case when $d=2$. In this paper, we prove that the conjecture is true for $d=3$ and $q \ge 8$. We further determine the second highest number of rational points on the intersection of a cubic surface and a non-degenerate Hermitian surface. Finally, we classify all the cubic surfaces that admit the highest and second highest number of points in common with a non-degenerate Hermitian surface. This classifications disproves one of the conjectures proposed by Edoukou, Ling and Xing.

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Peter Beelen, Mrinmoy Datta. 2018-02-19. Maximum number of points on intersection of a cubic surface and a non-degenerate Hermitian surface. https://arxiv.org/abs/1802.06681

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