Metamath Proof Explorer


Theorem 19.32v

Description: Version of 19.32 with a disjoint variable condition, requiring fewer axioms. (Contributed by BJ, 7-Mar-2020)

Ref Expression
Assertion 19.32v
|- ( A. x ( ph \/ ps ) <-> ( ph \/ A. x ps ) )

Proof

Step Hyp Ref Expression
1 19.21v
 |-  ( A. x ( -. ph -> ps ) <-> ( -. ph -> A. x ps ) )
2 df-or
 |-  ( ( ph \/ ps ) <-> ( -. ph -> ps ) )
3 2 albii
 |-  ( A. x ( ph \/ ps ) <-> A. x ( -. ph -> ps ) )
4 df-or
 |-  ( ( ph \/ A. x ps ) <-> ( -. ph -> A. x ps ) )
5 1 3 4 3bitr4i
 |-  ( A. x ( ph \/ ps ) <-> ( ph \/ A. x ps ) )