Metamath Proof Explorer


Theorem bj-drnf2v

Description: Version of drnf2 with a disjoint variable condition, which does not require ax-10 , ax-11 , ax-12 , ax-13 . Instance of nfbidv . Note that the version of axc15 with a disjoint variable condition is actually ax12v2 (up to adding a superfluous antecedent). (Contributed by BJ, 17-Jun-2019) (Proof modification is discouraged.)

Ref Expression
Hypothesis bj-drnf2v.1 x x = y φ ψ
Assertion bj-drnf2v x x = y z φ z ψ

Proof

Step Hyp Ref Expression
1 bj-drnf2v.1 x x = y φ ψ
2 1 nfbidv x x = y z φ z ψ