Elementary Class

Last updated Nov 1, 2022

Let $\mathcal{L}$ be a Language. We say that a Class of $\mathcal{L}$-Language Structures, $\mathcal{K}$ is an Elementary Class if there is an $\mathcal{L}$-Theory $T$ such that $\mathcal{K} = {\mathcal{M} : \mathcal{M} \models T}$.