Metamath Proof Explorer


Theorem nel2nelin

Description: Membership in an intersection implies membership in the second set. (Contributed by Glauco Siliprandi, 2-Jan-2022)

Ref Expression
Assertion nel2nelin ¬ A C ¬ A B C

Proof

Step Hyp Ref Expression
1 elinel2 A B C A C
2 1 con3i ¬ A C ¬ A B C