Theorem pm3.22

Theorem *3.22 of [WhiteheadRussell] p. 111. (Contributed by NM, 3-Jan-2005.) (Proof shortened by Wolf Lammen, 13-Nov-2012.)

Conclusion
\( \vdash \varphi \wedge \psi \rightarrow \psi \wedge \varphi \)
Proof
id
ancoms _