Metamath Proof Explorer


Theorem hbim1

Description: A closed form of hbim . (Contributed by NM, 2-Jun-1993)

Ref Expression
Hypotheses hbim1.1 φxφ
hbim1.2 φψxψ
Assertion hbim1 φψxφψ

Proof

Step Hyp Ref Expression
1 hbim1.1 φxφ
2 hbim1.2 φψxψ
3 2 a2i φψφxψ
4 1 19.21h xφψφxψ
5 3 4 sylibr φψxφψ