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 <> {}
by CAT_1:def 16;
then
( dom f = a & cod f = b )
by CAT_1:23;
hence
init a,b = f
by A1, Th43; verum