let O be set ; for G being GroupWithOperators of O holds HGrWOpStr(# the carrier of G, the multF of G, the action of G #) is StableSubgroup of G
let G be GroupWithOperators of O; HGrWOpStr(# the carrier of G, the multF of G, the action of G #) is StableSubgroup of G
reconsider G9 = HGrWOpStr(# the carrier of G, the multF of G, the action of G #) as non empty multMagma ;
A1:
now ex e9 being Element of G9 st
for h9 being Element of G9 holds
( h9 * e9 = h9 & e9 * h9 = h9 & ex g9 being Element of G9 st
( h9 * g9 = e9 & g9 * h9 = e9 ) )end;
now for x9, y9, z9 being Element of G9 holds (x9 * y9) * z9 = x9 * (y9 * z9)let x9,
y9,
z9 be
Element of
G9;
(x9 * y9) * z9 = x9 * (y9 * z9)reconsider x =
x9,
y =
y9,
z =
z9 as
Element of
G ;
(x9 * y9) * z9 =
(x * y) * z
.=
x * (y * z)
by GROUP_1:def 3
;
hence
(x9 * y9) * z9 = x9 * (y9 * z9)
;
verum end;
then reconsider G9 = G9 as non empty Group-like associative strict HGrWOpStr over O by A1, GROUP_1:def 2, GROUP_1:def 3;
for G being Group
for a being Action of O, the carrier of G st a = the action of G9 & multMagma(# the carrier of G, the multF of G #) = multMagma(# the carrier of G9, the multF of G9 #) holds
a is distributive
by Def5;
then reconsider G9 = G9 as non empty Group-like associative distributive HGrWOpStr over O by Def5;
the multF of G9 = the multF of G || the carrier of G9
;
then
G9 is Subgroup of G
by GROUP_2:def 5;
hence
HGrWOpStr(# the carrier of G, the multF of G, the action of G #) is StableSubgroup of G
by A2, Def7; verum