Metamath Proof Explorer

Theorem bj-tagn0

Description: The tagging of a class is nonempty. (Contributed by BJ, 6-Apr-2019)

Ref Expression
Assertion bj-tagn0 
|- tag A =/= (/)

Proof

Step Hyp Ref Expression
1 bj-0eltag 
 |-  (/) e. tag A
2 1 ne0ii 
 |-  tag A =/= (/)