theorem :: MEASUR13:37
for n being non zero Nat
for X being non-empty b1 + 1 -element FinSequence
for S being sigmaFieldFamily of X
for M being sigmaMeasureFamily of S
for f being PartFunc of (CarProduct X),ExtREAL
for E being Element of Prod_Field S
for g being PartFunc of [:(CarProduct (SubFin (X,n))),(ElmFin (X,(n + 1))):],ExtREAL st M is sigma_finite & E = dom f & f is E -measurable & f = g holds
( g is_integrable_on Prod_Measure ((Prod_Measure (SubFin (M,n))),(ElmFin (M,(n + 1)))) iff Integral ((Prod_Measure (SubFin (M,n))),(Integral2 ((ElmFin (M,(n + 1))),|.g.|))) < +infty )