Definition:Sequent

Definition
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.

Also presented as
Instead of presenting the sequent all on one line, separated by commas, it is often arranged in a vertical form:

Which form is preferred depends on personal taste or convenience.

A long sequent with complex premises is often better presented in the vertical form, whereas a simpler sequent which is easily comprehended at a glance may merit the single-line treatment.