Theorem simpr31

Simplification of conjunction. (Contributed by NM, 9-Mar-2012.) (Proof shortened by Wolf Lammen, 24-Jun-2022.)

Conclusion
\( \vdash \eta \wedge (\theta \wedge \tau \wedge (\varphi \wedge \psi \wedge \chi)) \rightarrow \varphi \)
Proof
simpr1
3ad2antr3 _