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Paul Hametner

Publications and source records attributed to Paul Hametner.

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Beating Product Constructions for Linear Equations Over Finite Fields

We show that for any $A\subseteq \mathbb{F}_q^n$ lacking non-trivial solutions to a translation-invariant linear equation of genus one, meaning that no nonempty proper subset of the coefficients sums to $0$, there is a set $B\subseteq \mathbb{F}_q^m$ in some higher dimension which also lacks non-trivial solutions, such that \[|B|^{1/m}>|A|^{1/n}.\] In particular, this implies that no fixed cap set in $\mathbb{F}_3^n$ gives an asymptotically optimal lower bound by direct products alone.

math.CO

The minimum degree question for the Maker Breaker Domination Game

The Maker Breaker Domination Game is a two player game played on a graph $G$ in which the players take turns to claim a vertex from the graph. The aim of the Dominator is to claim the vertices of a dominating set, and the aim of the Staller is to prevent this. In this paper, we consider the following problem: for a given integer $d$, what is the size of the smallest (with respect to the number of vertices) graph with minimum degree $d$ such that the Dominator loses going first? We write $\beta(d)$ to denote the answer to this question. We determine the precise value of $\beta(d)$ for $d\leq 3$. For general $d$ it was known that $2^{d+1} \leq \beta(d) \leq 2^{d+1}+2d$; the upper bound is due to a construction communicated to us by Valentin Gledel, while the lower bound follows from a simple application of the Erd\H{o}s-Selfridge Theorem. We improve the lower bound to $\beta(d) \geq 2^{d+1}+2$.

math.CO

Zero testing and equation solving for sparse polynomials on rectangular domains

We consider sparse polynomials in $N$ variables over a finite field, and ask whether they vanish on a set $S^N$, where $S$ is a set of nonzero elements of the field. We see that if for a polynomial $f$, there is $\mathbf{c}\in S^N$ with $f (\mathbf{c}) \neq 0$, then there is such a $\mathbf{c}$ in every sphere inside $S^N$, where the radius of the sphere is bounded by a multiple of the logarithm of the number of monomials that appear in $f$. A similar result holds for the solutions of the equations $f_1 = \cdots = f_r = 0$ inside $S^N$.

math.RA