\item Considering formulas $\varphi$ and $\psi$ regarding a theory $\Theory$. \begin{itemize} \item When is a formula $\varphi$ $\mathcal{T}$-valid? \item When is a formula $\varphi$ $\mathcal{T}$-satisfiable? \item When does $\varphi$ $\mathcal{T}$-entail $\psi$? \end{itemize}