Zero-one laws for existential first order sentences of bounded quantifier depth

Abstract

For any fixed positive integer $k$, let $\alpha_{k}$ denote the smallest $\alpha \in (0,1)$ such that the random graph sequence $\left\{G\left(n, n^{-\alpha}\right)\right\}$ does not satisfy the zero-one law for the set $\mathcal{E}_{k}$ of all existential first order sentences that are of quantifier depth at most $k$. This paper finds upper and lower bounds on $\alpha_{k}$, showing that as $k \rightarrow \infty$, we have $\alpha_{k} = \left(k - 2 - t(k)\right)^{-1}$ for some function $t(k) = \Theta(k^{-2})$. We also establish the precise value of $\alpha_{k}$ when $k = 4$.