Description: The monoid of endofunctions on a finite set A is finite. (Contributed by AV, 27-Jan-2024)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | efmndbas.g | |- G = ( EndoFMnd ` A ) | |
| efmndbas.b | |- B = ( Base ` G ) | ||
| Assertion | efmndbasfi | |- ( A e. Fin -> B e. Fin ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | efmndbas.g | |- G = ( EndoFMnd ` A ) | |
| 2 | efmndbas.b | |- B = ( Base ` G ) | |
| 3 | 1 2 | efmndbas | |- B = ( A ^m A ) | 
| 4 | mapfi | |- ( ( A e. Fin /\ A e. Fin ) -> ( A ^m A ) e. Fin ) | |
| 5 | 4 | anidms | |- ( A e. Fin -> ( A ^m A ) e. Fin ) | 
| 6 | 3 5 | eqeltrid | |- ( A e. Fin -> B e. Fin ) |