\begin{definition}[Definition:Sequent]
A '''sequent''' is an expression in the form:
:$\phi_1, \phi_2, \ldots, \phi_n \vdash \psi$
where $\phi_1, \phi_2, \ldots, \phi_n$ are premises (any number of them), and $\psi$ the conclusion (only one), of an argument.
\end{definition}