Metamath Proof Explorer


Theorem initoo

Description: An initial object is an object. (Contributed by AV, 14-Apr-2020)

Ref Expression
Assertion initoo
|- ( C e. Cat -> ( O e. ( InitO ` C ) -> O e. ( Base ` C ) ) )

Proof

Step Hyp Ref Expression
1 eqid
 |-  ( Base ` C ) = ( Base ` C )
2 eqid
 |-  ( Hom ` C ) = ( Hom ` C )
3 id
 |-  ( C e. Cat -> C e. Cat )
4 1 2 3 isinitoi
 |-  ( ( C e. Cat /\ O e. ( InitO ` C ) ) -> ( O e. ( Base ` C ) /\ A. b e. ( Base ` C ) E! h h e. ( O ( Hom ` C ) b ) ) )
5 4 simpld
 |-  ( ( C e. Cat /\ O e. ( InitO ` C ) ) -> O e. ( Base ` C ) )
6 5 ex
 |-  ( C e. Cat -> ( O e. ( InitO ` C ) -> O e. ( Base ` C ) ) )