Description: 2o is a set. (Contributed by BJ, 6-Apr-2019)
Ref | Expression | ||
---|---|---|---|
Assertion | 2oex | |- 2o e. _V |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-2o | |- 2o = suc 1o |
|
2 | 1oex | |- 1o e. _V |
|
3 | 2 | sucex | |- suc 1o e. _V |
4 | 1 3 | eqeltri | |- 2o e. _V |