Description: The intersection of two ordinal classes is ordinal. Proposition 7.9 of TakeutiZaring p. 37. (Contributed by NM, 9-May-1994)
Ref | Expression | ||
---|---|---|---|
Assertion | ordin | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ordtr | |
|
2 | ordtr | |
|
3 | trin | |
|
4 | 1 2 3 | syl2an | |
5 | inss2 | |
|
6 | trssord | |
|
7 | 5 6 | mp3an2 | |
8 | 4 7 | sylancom | |