Theorem pm5.3

Theorem *5.3 of [WhiteheadRussell] p. 125. (Contributed by NM, 3-Jan-2005.) (Proof shortened by Andrew Salmon, 7-May-2011.)

Conclusion
\( \vdash \varphi \wedge \psi \rightarrow \chi \leftrightarrow \varphi \wedge \psi \rightarrow \varphi \wedge \chi \)
Proof
simpl
biantrurd _
pm5.74i _