Description: Equality theorem for set recursion. (Contributed by Emmett Weisz, 17-Feb-2021)
Ref | Expression | ||
---|---|---|---|
Assertion | setrecseq | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fveq1 | |
|
2 | 1 | sseq1d | |
3 | 2 | imbi2d | |
4 | 3 | imbi2d | |
5 | 4 | albidv | |
6 | 5 | imbi1d | |
7 | 6 | albidv | |
8 | 7 | abbidv | |
9 | 8 | unieqd | |
10 | df-setrecs | |
|
11 | df-setrecs | |
|
12 | 9 10 11 | 3eqtr4g | |