let X be non empty set ; for S being SigmaField of X
for M being sigma_Measure of S
for f, g, f1, g1 being PartFunc of X,COMPLEX st f in L1_CFunctions M & f1 in L1_CFunctions M & g in L1_CFunctions M & g1 in L1_CFunctions M & a.e-Ceq-class (f,M) = a.e-Ceq-class (f1,M) & a.e-Ceq-class (g,M) = a.e-Ceq-class (g1,M) holds
a.e-Ceq-class ((f + g),M) = a.e-Ceq-class ((f1 + g1),M)
let S be SigmaField of X; for M being sigma_Measure of S
for f, g, f1, g1 being PartFunc of X,COMPLEX st f in L1_CFunctions M & f1 in L1_CFunctions M & g in L1_CFunctions M & g1 in L1_CFunctions M & a.e-Ceq-class (f,M) = a.e-Ceq-class (f1,M) & a.e-Ceq-class (g,M) = a.e-Ceq-class (g1,M) holds
a.e-Ceq-class ((f + g),M) = a.e-Ceq-class ((f1 + g1),M)
let M be sigma_Measure of S; for f, g, f1, g1 being PartFunc of X,COMPLEX st f in L1_CFunctions M & f1 in L1_CFunctions M & g in L1_CFunctions M & g1 in L1_CFunctions M & a.e-Ceq-class (f,M) = a.e-Ceq-class (f1,M) & a.e-Ceq-class (g,M) = a.e-Ceq-class (g1,M) holds
a.e-Ceq-class ((f + g),M) = a.e-Ceq-class ((f1 + g1),M)
let f, g, f1, g1 be PartFunc of X,COMPLEX; ( f in L1_CFunctions M & f1 in L1_CFunctions M & g in L1_CFunctions M & g1 in L1_CFunctions M & a.e-Ceq-class (f,M) = a.e-Ceq-class (f1,M) & a.e-Ceq-class (g,M) = a.e-Ceq-class (g1,M) implies a.e-Ceq-class ((f + g),M) = a.e-Ceq-class ((f1 + g1),M) )
assume that
A1:
( f in L1_CFunctions M & f1 in L1_CFunctions M & g in L1_CFunctions M & g1 in L1_CFunctions M )
and
A2:
( a.e-Ceq-class (f,M) = a.e-Ceq-class (f1,M) & a.e-Ceq-class (g,M) = a.e-Ceq-class (g1,M) )
; a.e-Ceq-class ((f + g),M) = a.e-Ceq-class ((f1 + g1),M)
( f a.e.cpfunc= f1,M & g a.e.cpfunc= g1,M )
by A1, A2, Th32;
then A3:
f + g a.e.cpfunc= f1 + g1,M
by Th25;
( f + g in L1_CFunctions M & f1 + g1 in L1_CFunctions M )
by A1, Th17;
hence
a.e-Ceq-class ((f + g),M) = a.e-Ceq-class ((f1 + g1),M)
by A3, Th32; verum