Metamath Proof Explorer


Theorem 0finOLD

Description: Obsolete version of 0fi as of 13-Jan-2025. (Contributed by FL, 14-Jul-2008) (Proof modification is discouraged.) (New usage is discouraged.)

Ref Expression
Assertion 0finOLD
|- (/) e. Fin

Proof

Step Hyp Ref Expression
1 peano1
 |-  (/) e. _om
2 ssid
 |-  (/) C_ (/)
3 ssnnfi
 |-  ( ( (/) e. _om /\ (/) C_ (/) ) -> (/) e. Fin )
4 1 2 3 mp2an
 |-  (/) e. Fin