Description: Obsolete version of cfon as of 10-Jun-2026. (Contributed by Mario Carneiro, 9-Mar-2013) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | cfonOLD | |- ( cf ` A ) e. On |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | cardcf | |- ( card ` ( cf ` A ) ) = ( cf ` A ) |
|
| 2 | cardon | |- ( card ` ( cf ` A ) ) e. On |
|
| 3 | 1 2 | eqeltrri | |- ( cf ` A ) e. On |