Description: Example for df-opab . Example by David A. Wheeler. (Contributed by Mario Carneiro, 18-Jun-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | ex-opab | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 3cn | |
|
2 | 4cn | |
|
3 | 3p1e4 | |
|
4 | 1 | elexi | |
5 | 2 | elexi | |
6 | eleq1 | |
|
7 | oveq1 | |
|
8 | 7 | eqeq1d | |
9 | 6 8 | 3anbi13d | |
10 | eleq1 | |
|
11 | eqeq2 | |
|
12 | 10 11 | 3anbi23d | |
13 | eqid | |
|
14 | 4 5 9 12 13 | brab | |
15 | 1 2 3 14 | mpbir3an | |
16 | breq | |
|
17 | 15 16 | mpbiri | |