let X be non empty set ; :: thesis: for S being SigmaField of X
for M being sigma_Measure of S
for f being PartFunc of X,ExtREAL st ex A being Element of S st
( A = dom f & f is_measurable_on A ) & f is nonnegative holds
0 <= Integral M,f

let S be SigmaField of X; :: thesis: for M being sigma_Measure of S
for f being PartFunc of X,ExtREAL st ex A being Element of S st
( A = dom f & f is_measurable_on A ) & f is nonnegative holds
0 <= Integral M,f

let M be sigma_Measure of S; :: thesis: for f being PartFunc of X,ExtREAL st ex A being Element of S st
( A = dom f & f is_measurable_on A ) & f is nonnegative holds
0 <= Integral M,f

let f be PartFunc of X,ExtREAL ; :: thesis: ( ex A being Element of S st
( A = dom f & f is_measurable_on A ) & f is nonnegative implies 0 <= Integral M,f )

assume A1: ( ex A being Element of S st
( A = dom f & f is_measurable_on A ) & f is nonnegative ) ; :: thesis: 0 <= Integral M,f
then 0 <= integral+ M,f by Th85;
hence 0 <= Integral M,f by A1, Th94; :: thesis: verum