Description: An ordinal number is a subset of On . (Contributed by NM, 11-Aug-1994)
Ref | Expression | ||
---|---|---|---|
Hypothesis | onssi.1 | |- A e. On |
|
Assertion | onssi | |- A C_ On |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | onssi.1 | |- A e. On |
|
2 | onss | |- ( A e. On -> A C_ On ) |
|
3 | 1 2 | ax-mp | |- A C_ On |