Description: Alternate definition of membership when the member is a set. (Contributed by NM, 18-Aug-1993) Strengthen from sethood hypothesis to sethood antecedent. (Revised by BJ, 12-Feb-2022) Avoid ax-12 . (Revised by BJ, 1-Sep-2024)
Ref | Expression | ||
---|---|---|---|
Assertion | clel2g | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | elisset | |
|
2 | biimt | |
|
3 | 1 2 | syl | |
4 | 19.23v | |
|
5 | eleq1 | |
|
6 | 5 | bicomd | |
7 | 6 | pm5.74i | |
8 | 7 | albii | |
9 | 4 8 | bitr3i | |
10 | 3 9 | bitrdi | |