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Metamath Proof Explorer


Theorem disjdifr

Description: A class and its relative complement are disjoint. (Contributed by Thierry Arnoux, 29-Nov-2023)

Ref Expression
Assertion disjdifr B A A =

Proof

Step Hyp Ref Expression
1 incom A B A = B A A
2 disjdif A B A =
3 1 2 eqtr3i B A A =