Metamath Proof Explorer


Theorem 2exbidv

Description: Formula-building rule for two existential quantifiers (deduction form). (Contributed by NM, 1-May-1995)

Ref Expression
Hypothesis 2albidv.1
|- ( ph -> ( ps <-> ch ) )
Assertion 2exbidv
|- ( ph -> ( E. x E. y ps <-> E. x E. y ch ) )

Proof

Step Hyp Ref Expression
1 2albidv.1
 |-  ( ph -> ( ps <-> ch ) )
2 1 exbidv
 |-  ( ph -> ( E. y ps <-> E. y ch ) )
3 2 exbidv
 |-  ( ph -> ( E. x E. y ps <-> E. x E. y ch ) )