Metamath Proof Explorer


Theorem pm5.32ri

Description: Distribution of implication over biconditional (inference form). (Contributed by NM, 12-Mar-1995)

Ref Expression
Hypothesis pm5.32i.1 φψχ
Assertion pm5.32ri ψφχφ

Proof

Step Hyp Ref Expression
1 pm5.32i.1 φψχ
2 1 pm5.32i φψφχ
3 ancom ψφφψ
4 ancom χφφχ
5 2 3 4 3bitr4i ψφχφ