Description: If a class is an element of another class, then its singleton is a subclass of that other class. Alternate proof of snssi . This theorem was automatically generated from snssiALTVD using a translation program. (Contributed by Alan Sare, 11-Sep-2011) (Proof modification is discouraged.) (New usage is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | snssiALT | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | velsn | |
|
2 | eleq1a | |
|
3 | 1 2 | syl5bi | |
4 | 3 | alrimiv | |
5 | dfss2 | |
|
6 | 4 5 | sylibr | |