Metamath Proof Explorer

Theorem nfel1

Description: Hypothesis builder for elementhood, special case. (Contributed by Mario Carneiro, 10-Oct-2016)

Ref Expression
Hypothesis nfeq1.1 
|- F/_ x A
Assertion nfel1 
|- F/ x A e. B

Proof

Step Hyp Ref Expression
1 nfeq1.1 
 |-  F/_ x A
2 nfcv 
 |-  F/_ x B
3 1 2 nfel 
 |-  F/ x A e. B