Description: Two ways of stating trichotomy with respect to inclusion. (Contributed by NM, 12-Aug-2004)
Ref | Expression | ||
---|---|---|---|
Assertion | sspsstri | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | or32 | |
|
2 | sspss | |
|
3 | sspss | |
|
4 | eqcom | |
|
5 | 4 | orbi2i | |
6 | 3 5 | bitri | |
7 | 2 6 | orbi12i | |
8 | orordir | |
|
9 | 7 8 | bitr4i | |
10 | df-3or | |
|
11 | 1 9 10 | 3bitr4i | |