Metamath Proof Explorer


Theorem finonex

Description: The finite ordinals are a set. See also onprc and fiprc for proof that On and Fin are proper classes. (Contributed by RP, 27-Sep-2023)

Ref Expression
Assertion finonex ( On ∩ Fin ) ∈ V

Proof

Step Hyp Ref Expression
1 onfin2 ω = ( On ∩ Fin )
2 omex ω ∈ V
3 1 2 eqeltrri ( On ∩ Fin ) ∈ V