theorem Th26: :: INTEGRA6:26
for a, b, e being Real
for f being PartFunc of REAL,REAL st a <= b & ['a,b'] c= dom f & ( for x being Real st x in ['a,b'] holds
f . x = e ) holds
( f is_integrable_on ['a,b'] & f | ['a,b'] is bounded & integral (f,a,b) = e * (b - a) )