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Related theorems Unicode version |
| Description: A function's value belongs to its codomain. |
| Ref | Expression |
|---|---|
| ffvelrn |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | fnfvelrn 3804 |
. . 3
| |
| 2 | ffn 3619 |
. . 3
| |
| 3 | 1, 2 | sylan 448 |
. 2
|
| 4 | frn 3624 |
. . . 4
| |
| 5 | 4 | sseld 2063 |
. . 3
|
| 6 | 5 | adantr 389 |
. 2
|
| 7 | 3, 6 | mpd 26 |
1
|