Line-Plane Incidence Bound in $\mathbb{R}^4$

Abstract

We consider an incidence problem in $\mathbb{R}^4$ which asks, for a set of $L$ lines and a set of $S$ planes in general position, what the maximum number of line-plane incidences is. A line-plane incidence is defined as a point where a line and a plane intersect. We prove that, when the lines and planes are in a truly 4-dimensional configuration such that no more than $L^{\frac{1}{2}+\epsilon}$ lines are contained in any 2-dimensional surface of degree at most $D$ and no more than $S^{\frac{1}{2}+\epsilon}$ 2-planes are contained in any 3-dimensional hypersurface of degree at most $D$, and if $L^{1/2} \ll S \ll L$, then for a constant $D>1$ and an $\epsilon>0$ there exists a non-trivial upper bound for incidences between lines and planes: $L^{\frac{3}{4}+\frac{1}{2}\epsilon}S + LS^{\frac{1}{2}+\epsilon}$. We also prove several supporting lemmas.