Description: Obsolete version of bdaydm as of 10-Jun-2026. (Contributed by Scott Fenton, 14-Jun-2011) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | bdaydmOLD | |- dom bday = No |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | bdayfo | |- bday : No -onto-> On |
|
| 2 | fof | |- ( bday : No -onto-> On -> bday : No --> On ) |
|
| 3 | 1 2 | ax-mp | |- bday : No --> On |
| 4 | 3 | fdmi | |- dom bday = No |