A Szemerédi-Trotter Theorem in Arbitrary Fields
Abstract
Let k be a field of characteristic p≥0. We prove that m points and n lines in k2 determine at most 3(mn)2/3+m+n+2mn/p incidences, the last term being omitted in characteristic zero. Over the prime field 𝔽p the coefficient of mn/p can be replaced by $1$. The proof uses the polynomial method, and for m=n the bound is sharp up to an absolute constant over prime fields. As applications, over prime fields in which −1 is not a square we obtain the L2→ Lr extension estimate for the paraboloid in 𝔽p3 for r>10/3. Over every odd prime field, we show that a two-source extractor construction of Bourgain has exponentially small error at every min-entropy rate greater than 1/3. We also improve sum-product estimates for small sets in positive characteristic and obtain projection and Furstenberg estimates over prime fields. The incidence inequalities with exact constants have been formalized in Lean.
Related
BibTeX
@misc{lewko2026szemeréditrotter,
title = {{A Szemerédi-Trotter Theorem in Arbitrary Fields}},
author = {Mark Lewko},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.27023},
eprint = {2609.27023},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.27023},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A Szemerédi-Trotter Theorem in Arbitrary Fields
AU - Mark Lewko
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2609.27023
UR - https://arxiv.org/abs/2609.27023
AB - Let k be a field of characteristic p≥0. We prove that m points and n lines in k^2 determine at most 3(mn)^2/3+m+n+2mn/p incidences, the last term being omitted in characteristic zero. Over the prime field 𝔽_p the coefficient of mn/p can be replaced by $1$. The proof uses the polynomial method, and for m=n the bound is sharp up to an absolute constant over prime fields. As applications, over prime fields in which −1 is not a square we obtain the L^2→ L^r extension estimate for the paraboloid in 𝔽_p^3 for r>10/3. Over every odd prime field, we show that a two-source extractor construction of Bourgain has exponentially small error at every min-entropy rate greater than 1/3. We also improve sum-product estimates for small sets in positive characteristic and obtain projection and Furstenberg estimates over prime fields. The incidence inequalities with exact constants have been formalized in Lean.
ER -