for X being non empty set
for S being SigmaField of X
for M being sigma_Measure of S
for f being PartFunc of X,ExtREAL
for F being Finite_Sep_Sequence of S
for a being FinSequence of ExtREAL
for n being Nat st f is_simple_func_in S & F,a are_Re-presentation_of f & n in dom F & not F . n = {} holds
a . n is Real