Metamath Proof Explorer


Theorem ab0orvALT

Description: Alternate proof of ab0orv , shorter but using more axioms. (Contributed by Mario Carneiro, 29-Aug-2013) (Revised by BJ, 22-Mar-2020) (Proof modification is discouraged.) (New usage is discouraged.)

Ref Expression
Assertion ab0orvALT x | φ = V x | φ =

Proof

Step Hyp Ref Expression
1 nfv x φ
2 dfnf5 x φ x | φ = V x | φ =
3 1 2 mpbi x | φ = V x | φ =