Description: If A is a proper class, then the recursive function generator at (/) is the empty set. (Contributed by Scott Fenton, 31-Oct-2024)
Ref | Expression | ||
---|---|---|---|
Assertion | rdg0n | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0elon | |
|
2 | df-rdg | |
|
3 | 2 | tfr2 | |
4 | 1 3 | ax-mp | |
5 | res0 | |
|
6 | 5 | fveq2i | |
7 | 4 6 | eqtri | |
8 | iftrue | |
|
9 | eqid | |
|
10 | 8 9 | fvmptn | |
11 | 7 10 | eqtrid | |