theorem Th20: :: MESFUN6C:20

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,REAL
for E, A being Element of S st ex E being Element of S st
( E = dom f & f is E -measurable ) & M . A = 0 holds
f | A is_integrable_on M by Th19;