Theorem exp45

An exportation inference. (Contributed by NM, 26-Apr-1994.)

Hypothesis
exp45.1
\( \vdash \varphi \wedge (\psi \wedge (\chi \wedge \theta)) \rightarrow \tau \)
Conclusion
\( \vdash \varphi \rightarrow \psi \rightarrow \chi \rightarrow \theta \rightarrow \tau \)
Proof
exp45.1
exp32 _
exp4a _