Theorem simp231

Simplification of conjunction. (Contributed by NM, 9-Mar-2012.)

Conclusion
\( \vdash \eta \wedge (\theta \wedge \tau \wedge (\varphi \wedge \psi \wedge \chi)) \wedge \zeta \rightarrow \varphi \)
Proof
simp31
3ad2ant2 _