\begin{itemize}
    \item \emph{Constants} in $\Sigma$, \emph{variables}, and
    applications of function symbols in $\Sigma$ where all inputs are $\mathcal{T}$-terms are $\mathcal{T}$-terms.
    \item A $\mathcal{T}$-atom is the application of a predicate symbol in $\Sigma$ where all inputs are $\mathcal{T}$-terms.
    \item A $\mathcal{T}$-literal is a $\mathcal{T}$-atoms or its negation.
\end{itemize}