Description: Possible values for a set sandwiched between another set and it plus a singleton. (Contributed by Mario Carneiro, 2-Jul-2016)
Ref | Expression | ||
---|---|---|---|
Assertion | ssunsn | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ssunsn2 | |
|
2 | ancom | |
|
3 | eqss | |
|
4 | 2 3 | bitr4i | |
5 | ancom | |
|
6 | eqss | |
|
7 | 5 6 | bitr4i | |
8 | 4 7 | orbi12i | |
9 | 1 8 | bitri | |