Metamath Proof Explorer


Theorem simp223

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

Ref Expression
Assertion simp223 ηθφψχτζχ

Proof

Step Hyp Ref Expression
1 simp23 θφψχτχ
2 1 3ad2ant2 ηθφψχτζχ