2 problems

Let $\mathcal C$ be a hereditary class of finite structures, and let $\tilde{\mathcal C}_{\leq \omega}$ be the class of countable structures whose age is included in $\mathcal C$.…

Let $\mathfrak A$ be an age in a finite relational language, and let $\operatorname{Mod}(\mathfrak A)/{\equiv}$ denote the bi-embeddability classes of countable structures with age…