Definition:Gentzen Proof System/Instance 1/Beta-Rule/Notation

Definition
Let $\mathscr G$ be instance 1 of a Gentzen proof system.

Let $\mathbf B$ be a $\beta$-formula, with $\mathbf B_1, \mathbf B_2$ as in the table of $\beta$-formulas.

In a tableau proof, the $\beta$-rule can be used as follows: