let X be non empty set ; for S being SigmaField of X
for f being PartFunc of X,COMPLEX
for B, A being Element of S st f is_measurable_on B & A = (dom f) /\ B holds
f | B is_measurable_on A
let S be SigmaField of X; for f being PartFunc of X,COMPLEX
for B, A being Element of S st f is_measurable_on B & A = (dom f) /\ B holds
f | B is_measurable_on A
let f be PartFunc of X,COMPLEX ; for B, A being Element of S st f is_measurable_on B & A = (dom f) /\ B holds
f | B is_measurable_on A
let B, A be Element of S; ( f is_measurable_on B & A = (dom f) /\ B implies f | B is_measurable_on A )
assume that
A1:
f is_measurable_on B
and
A2:
A = (dom f) /\ B
; f | B is_measurable_on A
A3:
A = (dom (Im f)) /\ B
by A2, COMSEQ_3:def 4;
Im f is_measurable_on B
by A1, Def3;
then
(Im f) | B is_measurable_on A
by A3, MESFUNC6:76;
then A4:
Im (f | B) is_measurable_on A
by Th7;
A5:
A = (dom (Re f)) /\ B
by A2, COMSEQ_3:def 3;
Re f is_measurable_on B
by A1, Def3;
then
(Re f) | B is_measurable_on A
by A5, MESFUNC6:76;
then
Re (f | B) is_measurable_on A
by Th7;
hence
f | B is_measurable_on A
by A4, Def3; verum