consider f1 being morphism of (OrdC 2) such that
A1:
not f1 is identity
and
Ob (OrdC 2) = {(dom f1),(cod f1)}
and
A2:
Mor (OrdC 2) = {(dom f1),(cod f1),f1}
and
A3:
dom f1, cod f1,f1 are_mutually_distinct
by Th39;
defpred S1[ object , object ] means ( ( $1 = dom f1 implies $2 = dom f ) & ( $1 = cod f1 implies $2 = cod f ) & ( $1 = f1 implies $2 = f ) );
A4:
for x being object st x in the carrier of (OrdC 2) holds
ex y being object st
( y in the carrier of C & S1[x,y] )
consider F being Function of the carrier of (OrdC 2), the carrier of C such that
A9:
for x being object st x in the carrier of (OrdC 2) holds
S1[x,F . x]
from FUNCT_2:sch 1(A4);
reconsider F = F as Functor of (OrdC 2),C ;
for g being morphism of (OrdC 2) st g is identity holds
F . g is identity
then A12:
F is identity-preserving
by CAT_6:def 22;
for g1, g2 being morphism of (OrdC 2) st g1 |> g2 holds
( F . g1 |> F . g2 & F . (g1 (*) g2) = (F . g1) (*) (F . g2) )
then reconsider F = F as covariant Functor of (OrdC 2),C by A12, CAT_6:def 23, CAT_6:def 25;
take
F
; for g being morphism of (OrdC 2) st not g is identity holds
F . g = f
let g be morphism of (OrdC 2); ( not g is identity implies F . g = f )
assume A37:
not g is identity
; F . g = f
A38:
( g = dom f1 or g = cod f1 or g = f1 )
by A2, ENUMSET1:def 1;
reconsider x = g as object ;
A39:
F . x = F . g
by CAT_6:def 21;
g in Mor (OrdC 2)
;
then
x in the carrier of (OrdC 2)
by CAT_6:def 1;
hence
F . g = f
by A9, A38, A39, A37, CAT_6:22; verum