Metamath Proof Explorer


Theorem nfcrd

Description: Consequence of the not-free predicate. (Contributed by Mario Carneiro, 11-Aug-2016)

Ref Expression
Hypothesis nfcrd.1 φ _ x A
Assertion nfcrd φ x y A

Proof

Step Hyp Ref Expression
1 nfcrd.1 φ _ x A
2 nfcr _ x A x y A
3 1 2 syl φ x y A