Description: The intersection of two ordinal numbers is an ordinal number. (Contributed by NM, 7-Apr-1995)
Ref | Expression | ||
---|---|---|---|
Assertion | onin | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eloni | |
|
2 | eloni | |
|
3 | ordin | |
|
4 | 1 2 3 | syl2an | |
5 | simpl | |
|
6 | inex1g | |
|
7 | elong | |
|
8 | 5 6 7 | 3syl | |
9 | 4 8 | mpbird | |