Description: Obsolete version of 1on as of 30-Nov-2024. (Contributed by NM, 29-Oct-1995) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | 1onOLD | |- 1o e. On |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | df-1o | |- 1o = suc (/) |
|
| 2 | 0elon | |- (/) e. On |
|
| 3 | 2 | onsuci | |- suc (/) e. On |
| 4 | 1 3 | eqeltri | |- 1o e. On |