The classical ErdH{o}s-Littlewood-Offord theorem says that for nonzero vectors $a_1,dots,a_nin mathbb{R}^d$, any $xin mathbb{R}^d$, and uniformly random $(xi_1,dots,xi_n)in{-1,1}^n$, we have $Pr(a_1xi_1+dots+a_nxi_n=x)=O(n^{-1/2})$. In this paper we
show that $Pr(a_1xi_1+dots+a_nxi_nin S)le n^{-1/2+o(1)}$ whenever $S$ is definable with respect to an o-minimal structure (for example, this holds when $S$ is any algebraic hypersurface), under the necessary condition that it does not contain a line segment. We also obtain an inverse theorem in this setting.
We compute the $GL_{r+1}$-equivariant Chow class of the $GL_{r+1}$-orbit closure of any point $(x_1, ldots, x_n) in (mathbb{P}^r)^n$ in terms of the rank polytope of the matroid represented by $x_1, ldots, x_n in mathbb{P}^r$. Using these classes and
generalizations involving point configurations in higher dimensional projective spaces, we define for each $dtimes n$ matrix $M$ an $n$-ary operation $[M]_hbar$ on the small equivariant quantum cohomology ring of $mathbb{P}^r$, which is the $n$-ary quantum product when $M$ is an invertible matrix. We prove that $M mapsto [M]_hbar$ is a valuative matroid polytope association. Like the quantum product, these operations satisfy recursive properties encoding solutions to enumerative problems involving point configurations of given moduli in a relative setting. As an application, we compute the number of line sections with given moduli of a general degree $2r+1$ hypersurface in $mathbb{P}^r$, generalizing the known case of quintic plane curves.
