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Metamath Proof Explorer

Theorem negex

Description: A negative is a set. (Contributed by NM, 4-Apr-2005)

Ref Expression
Assertion negex 
|- -u A e. _V

Proof

Step Hyp Ref Expression
1 df-neg 
 |-  -u A = ( 0 - A )
2 1 ovexi 
 |-  -u A e. _V