Metamath Proof Explorer


Theorem pm4.76

Description: Theorem *4.76 of WhiteheadRussell p. 121. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm4.76 φψφχφψχ

Proof

Step Hyp Ref Expression
1 jcab φψχφψφχ
2 1 bicomi φψφχφψχ