Metamath Proof Explorer

Theorem nfmo

Description: Bound-variable hypothesis builder for the at-most-one quantifier. Note that x and y need not be disjoint. Usage of this theorem is discouraged because it depends on ax-13 . Use the weaker nfmov when possible. (Contributed by NM, 9-Mar-1995) (New usage is discouraged.)

Ref Expression
Hypothesis nfmo.1 x φ
Assertion nfmo x * y φ


Step Hyp Ref Expression
1 nfmo.1 x φ
2 nftru y
3 1 a1i x φ
4 2 3 nfmod x * y φ
5 4 mptru x * y φ