Erd\H{o}s-Selfridge Theorem for Nonmonotone CNFs

TL;DR

This paper extends the Erd ext{"o}s-Selfridge theorem to nonmonotone CNFs, establishing bounds on the minimum number of clauses for Maker to win in a Maker-Breaker game, revealing new asymptotic behaviors.

Contribution

It generalizes the Erd ext{"o}s-Selfridge theorem from monotone to nonmonotone CNFs, providing new bounds on clause counts for winning strategies.

Findings

Bounds of ()^{k} for Maker when playing last

Bounds of (1.5)^k and r^k for Breaker when playing last

Extension of classical theorem to nonmonotone CNFs

Abstract

In an influential paper, Erd\H{o}s and Selfridge introduced the Maker-Breaker game played on a hypergraph, or equivalently, on a monotone CNF. The players take turns assigning values to variables of their choosing, and Breaker's goal is to satisfy the CNF, while Maker's goal is to falsify it. The Erd\H{o}s-Selfridge Theorem says that the least number of clauses in any monotone CNF with $k$ literals per clause where Maker has a winning strategy is $\Theta(2^k)$. We study the analogous question when the CNF is not necessarily monotone. We prove bounds of $\Theta(\sqrt{2}\,^k)$ when Maker plays last, and $\Omega(1.5^k)$ and $O(r^k)$ when Breaker plays last, where $r=(1+\sqrt{5})/2\approx 1.618$ is the golden ratio.