Metamath Proof Explorer


Theorem baib

Description: Move conjunction outside of biconditional. (Contributed by NM, 13-May-1999)

Ref Expression
Hypothesis baib.1 φψχ
Assertion baib ψφχ

Proof

Step Hyp Ref Expression
1 baib.1 φψχ
2 ibar ψχψχ
3 1 2 bitr4id ψφχ