Theorem exp4c

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

Hypothesis
exp4c.1
\( \vdash \varphi \rightarrow \psi \wedge \chi \wedge \theta \rightarrow \tau \)
Conclusion
\( \vdash \varphi \rightarrow \psi \rightarrow \chi \rightarrow \theta \rightarrow \tau \)
Proof
exp4c.1
expd _
expd _