Rule of Commutation/Disjunction/Formulation 2/Forward Implication

Theorem

 * $\vdash \left({p \lor q}\right) \implies \left({q \lor p}\right)$

Proof
Using a tableau proof for instance 1 of a Gentzen proof system:

Also see

 * This is an axiom of the following proof system:
 * Definition:Hilbert Proof System/Instance 2