Metamath Proof Explorer

Theorem neldifsnd

Description: The class A is not in ( B \ { A } ) . Deduction form. (Contributed by David Moews, 1-May-2017)

Ref Expression
Assertion neldifsnd 
|- ( ph -> -. A e. ( B \ { A } ) )

Proof

Step Hyp Ref Expression
1 neldifsn 
 |-  -. A e. ( B \ { A } )
2 1 a1i 
 |-  ( ph -> -. A e. ( B \ { A } ) )