Rule of Assumption/Proof Rule/Tableau Form

Proof Rule
Let $\phi$ be a propositional formula.

The Rule of Assumption is invoked for $\phi$ in a tableau proof in the following manner:

Note that the Description: field of the Rule of Assumption is populated with either:
 * $(1): \quad$ Premise if the statement being assumed is one of the premises of the argument

or:
 * $(2): \quad$ Assumption if it is to be discharged later in the proof.

On completion of the proof, only those lines annotated Premise are to remain in the pool of assumptions of the conclusion.

Also defined as
Some sources introduce the formula line as:
 * Show $\phi$