Description: Existence of a class of subsets. (Contributed by NM, 15-Jul-2006) (Proof shortened by Andrew Salmon, 25-Jul-2011)
Ref | Expression | ||
---|---|---|---|
Assertion | abssexg | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pwexg | |
|
2 | df-pw | |
|
3 | 2 | eleq1i | |
4 | simpl | |
|
5 | 4 | ss2abi | |
6 | ssexg | |
|
7 | 5 6 | mpan | |
8 | 3 7 | sylbi | |
9 | 1 8 | syl | |