Theorem imp4a

An importation inference. (Contributed by NM, 26-Apr-1994.) (Proof shortened by Wolf Lammen, 19-Jul-2021.)

Hypothesis
imp4.1
\( \vdash \varphi \rightarrow \psi \rightarrow \chi \rightarrow \theta \rightarrow \tau \)
Conclusion
\( \vdash \varphi \rightarrow \psi \rightarrow \chi \wedge \theta \rightarrow \tau \)
Proof
imp4.1
imp4b _
ex _