let C be Category; for a, b being Object of C
for f being Morphism of a,b st a is initial holds
init (a,b) = f
let a, b be Object of C; for f being Morphism of a,b st a is initial holds
init (a,b) = f
let f be Morphism of a,b; ( a is initial implies init (a,b) = f )
assume A1:
a is initial
; init (a,b) = f
then
Hom (a,b) <> {}
;
then
( dom f = a & cod f = b )
by CAT_1:5;
hence
init (a,b) = f
by A1, Th39; verum