let UN be Universe; for f being Morphism of
for f' being Element of Morphs (GroupObjects UN)
for b being Object of
for b' being Element of GroupObjects UN holds
( f is strict Element of Morphs (GroupObjects UN) & f' is Morphism of & b is strict Element of GroupObjects UN & b' is Object of )
set C = GroupCat UN;
set V = GroupObjects UN;
set X = Morphs (GroupObjects UN);
let f be Morphism of ; for f' being Element of Morphs (GroupObjects UN)
for b being Object of
for b' being Element of GroupObjects UN holds
( f is strict Element of Morphs (GroupObjects UN) & f' is Morphism of & b is strict Element of GroupObjects UN & b' is Object of )
let f' be Element of Morphs (GroupObjects UN); for b being Object of
for b' being Element of GroupObjects UN holds
( f is strict Element of Morphs (GroupObjects UN) & f' is Morphism of & b is strict Element of GroupObjects UN & b' is Object of )
let b be Object of ; for b' being Element of GroupObjects UN holds
( f is strict Element of Morphs (GroupObjects UN) & f' is Morphism of & b is strict Element of GroupObjects UN & b' is Object of )
let b' be Element of GroupObjects UN; ( f is strict Element of Morphs (GroupObjects UN) & f' is Morphism of & b is strict Element of GroupObjects UN & b' is Object of )
consider x being set such that
x in UN
and
A1:
GO x,b
by Def29;
ex G, H being strict Element of GroupObjects UN st f is strict Morphism of G,H
by Def30;
hence
f is strict Element of Morphs (GroupObjects UN)
; ( f' is Morphism of & b is strict Element of GroupObjects UN & b' is Object of )
thus
f' is Morphism of
; ( b is strict Element of GroupObjects UN & b' is Object of )
ex x1, x2, x3, x4 being set st
( x = [x1,x2,x3,x4] & ex G being strict AddGroup st
( b = G & x1 = the carrier of G & x2 = the addF of G & x3 = comp G & x4 = 0. G ) )
by A1, Def28;
hence
b is strict Element of GroupObjects UN
; b' is Object of
thus
b' is Object of
; verum