Metamath Proof Explorer

Theorem bj-2exbi

Description: Closed form of 2exbii . (Contributed by BJ, 6-May-2019)

Ref Expression
Assertion bj-2exbi 
|- ( A. x A. y ( ph <-> ps ) -> ( E. x E. y ph <-> E. x E. y ps ) )

Proof

Step Hyp Ref Expression
1 exbi 
 |-  ( A. y ( ph <-> ps ) -> ( E. y ph <-> E. y ps ) )
2 1 alexbii 
 |-  ( A. x A. y ( ph <-> ps ) -> ( E. x E. y ph <-> E. x E. y ps ) )