let X1, X2 be non empty set ; for S1 being SigmaField of X1
for S2 being SigmaField of X2
for M2 being sigma_Measure of S2
for f being PartFunc of [:X1,X2:],ExtREAL
for E1, E2 being Element of sigma (measurable_rectangles (S1,S2))
for U being Element of S1 st M2 is sigma_finite & ( f is nonnegative or f is nonpositive ) & E1 = dom f & f is E1 -measurable holds
Integral2 (M2,(f | E2)) is U -measurable
let S1 be SigmaField of X1; for S2 being SigmaField of X2
for M2 being sigma_Measure of S2
for f being PartFunc of [:X1,X2:],ExtREAL
for E1, E2 being Element of sigma (measurable_rectangles (S1,S2))
for U being Element of S1 st M2 is sigma_finite & ( f is nonnegative or f is nonpositive ) & E1 = dom f & f is E1 -measurable holds
Integral2 (M2,(f | E2)) is U -measurable
let S2 be SigmaField of X2; for M2 being sigma_Measure of S2
for f being PartFunc of [:X1,X2:],ExtREAL
for E1, E2 being Element of sigma (measurable_rectangles (S1,S2))
for U being Element of S1 st M2 is sigma_finite & ( f is nonnegative or f is nonpositive ) & E1 = dom f & f is E1 -measurable holds
Integral2 (M2,(f | E2)) is U -measurable
let M2 be sigma_Measure of S2; for f being PartFunc of [:X1,X2:],ExtREAL
for E1, E2 being Element of sigma (measurable_rectangles (S1,S2))
for U being Element of S1 st M2 is sigma_finite & ( f is nonnegative or f is nonpositive ) & E1 = dom f & f is E1 -measurable holds
Integral2 (M2,(f | E2)) is U -measurable
let f be PartFunc of [:X1,X2:],ExtREAL; for E1, E2 being Element of sigma (measurable_rectangles (S1,S2))
for U being Element of S1 st M2 is sigma_finite & ( f is nonnegative or f is nonpositive ) & E1 = dom f & f is E1 -measurable holds
Integral2 (M2,(f | E2)) is U -measurable
let E, A be Element of sigma (measurable_rectangles (S1,S2)); for U being Element of S1 st M2 is sigma_finite & ( f is nonnegative or f is nonpositive ) & E = dom f & f is E -measurable holds
Integral2 (M2,(f | A)) is U -measurable
let U be Element of S1; ( M2 is sigma_finite & ( f is nonnegative or f is nonpositive ) & E = dom f & f is E -measurable implies Integral2 (M2,(f | A)) is U -measurable )
assume that
A1:
M2 is sigma_finite
and
A2:
( f is nonnegative or f is nonpositive )
and
A3:
E = dom f
and
A4:
f is E -measurable
; Integral2 (M2,(f | A)) is U -measurable
A5:
dom (f | A) = E /\ A
by A3, RELAT_1:61;
A6:
(dom f) /\ (E /\ A) = E /\ A
by A3, XBOOLE_1:17, XBOOLE_1:28;
f is E /\ A -measurable
by A4, XBOOLE_1:17, MESFUNC1:30;
then
f | (E /\ A) is E /\ A -measurable
by A6, MESFUNC5:42;
then
(f | E) | A is E /\ A -measurable
by RELAT_1:71;
hence
Integral2 (M2,(f | A)) is U -measurable
by A1, A2, A3, A5, MESFUNC5:15, MESFUN11:1, Th60; verum