theorem Th1922: :: INTEGR21:22

for a, b, c, d being Real
for Y being RealBanachSpace
for f being continuous PartFunc of REAL, the carrier of Y st a <= b & ['a,b'] c= dom f & c in ['a,b'] & d in ['a,b'] holds
( ||.f.|| is_integrable_on ['(min (c,d)),(max (c,d))'] & ||.f.|| | ['(min (c,d)),(max (c,d))'] is bounded & ||.(integral (f,c,d)).|| <= integral (||.f.||,(min (c,d)),(max (c,d))) )