let X be non empty set ; for S being SigmaField of X
for f, g being PartFunc of X,REAL
for A being Element of S st A c= dom f & f is_measurable_on A & g is_measurable_on A holds
(max+ (f + g)) + (max- f) is_measurable_on A
let S be SigmaField of X; for f, g being PartFunc of X,REAL
for A being Element of S st A c= dom f & f is_measurable_on A & g is_measurable_on A holds
(max+ (f + g)) + (max- f) is_measurable_on A
let f, g be PartFunc of X,REAL ; for A being Element of S st A c= dom f & f is_measurable_on A & g is_measurable_on A holds
(max+ (f + g)) + (max- f) is_measurable_on A
let A be Element of S; ( A c= dom f & f is_measurable_on A & g is_measurable_on A implies (max+ (f + g)) + (max- f) is_measurable_on A )
assume that
A1:
A c= dom f
and
A2:
f is_measurable_on A
and
A3:
g is_measurable_on A
; (max+ (f + g)) + (max- f) is_measurable_on A
f + g is_measurable_on A
by A2, A3, Th26;
then A4:
max+ (f + g) is_measurable_on A
by Th46;
max- f is_measurable_on A
by A1, A2, Th47;
hence
(max+ (f + g)) + (max- f) is_measurable_on A
by A4, Th26; verum