let R be comRing; for M being LeftMod of R holds canHom M is multiplicative
let M be LeftMod of R; canHom M is multiplicative
for x, y being Element of R holds (canHom M) . (x * y) = ((canHom M) . x) * ((canHom M) . y)
proof
let x,
y be
Element of
R;
(canHom M) . (x * y) = ((canHom M) . x) * ((canHom M) . y)
consider f being
Endomorphism of
R,
M such that A1:
(
f = (curry the lmult of M) . x &
(canHom M) . x = AbGr f )
by Def27;
consider g being
Endomorphism of
R,
M such that A2:
(
g = (curry the lmult of M) . y &
(canHom M) . y = AbGr g )
by Def27;
consider h being
Endomorphism of
R,
M such that A3:
(
h = (curry the lmult of M) . (x * y) &
(canHom M) . (x * y) = AbGr h )
by Def27;
reconsider f0 =
f,
g0 =
g,
h0 =
h as
Element of
Funcs ( the
carrier of
M, the
carrier of
M)
by FUNCT_2:8;
A4:
for
m being
Element of
M holds
h . m = (f * g) . m
reconsider f1 =
AbGr f,
g1 =
AbGr g as
Endomorphism of
(AbGr M) by Th28;
h = f * g
by A4;
then (canHom M) . (x * y) =
(FuncComp (AbGr M)) . (
f1,
g1)
by A3, Th34
.=
((canHom M) . x) * ((canHom M) . y)
by A1, A2, Th6
;
hence
(canHom M) . (x * y) = ((canHom M) . x) * ((canHom M) . y)
;
verum
end;
hence
canHom M is multiplicative
by GROUP_6:def 6; verum