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Metamath Proof Explorer

Theorem prtlem80

Description: Lemma for prter2 . (Contributed by Rodolfo Medina, 17-Oct-2010)

Ref Expression
Assertion prtlem80 
|- ( A e. B -> -. A e. ( C \ { A } ) )

Proof

Step Hyp Ref Expression
1 neldifsnd 
 |-  ( A e. B -> -. A e. ( C \ { A } ) )