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Given positive integers $k\leq d$ and a finite field $\mathbb{F}$, a set$S\subset\mathbb{F}^{d}$ is $(k,c)$-subspace evasive if every $k$-dimensionalaffine subspace contains at most $c$ elements of $S$. By a simple averagingargument, the maximum size of a $(k,c)$-subspace evasive set is at most $c|\mathbb{F}|^{d-k}$. When $k$ and $d$ are fixed, and $c$ is sufficiently large,the matching lower bound $\Omega(|\mathbb{F}|^{d-k})$ is proved by Dvir andLovett. We provide an alternative proof of this result using the randomalgebraic method. We also prove sharp upper bounds on the size of$(k,c)$-evasive sets in case $d$ is large, extending results of Ben-Aroya andShinkar.  The existence of optimal evasive sets has several interesting consequences incombinatorial geometry. We show that the minimum number of $k$-dimensionallinear hyperplanes needed to cover the grid $[n]^{d}\subset \mathbb{R}^{d}$ is$\Omega_{d}\big(n^{\frac{d(d-k)}{d-1}}\big)$, which matches the upper boundproved by Balko, Cibulka, and Valtr, and settles a problem proposed by Brass,Moser, and Pach. Furthermore, we improve the best known lower bound on themaximum number of incidences between points and hyperplanes in $\mathbb{R}^{d}$assuming their incidence graph avoids the complete bipartite graph $K_{c,c}$for some large constant $c=c(d)$.

Evasive sets, covering by subspaces, and point-hyperplane incidences