theorem
for
a,
b,
c being
Real for
f being
Function of
REAL,
REAL st
a < b &
b < c &
f is_integrable_on ['a,c'] &
f | ['a,c'] is
bounded holds
(
f is_integrable_on ['a,b'] &
f is_integrable_on ['b,c'] &
f | ['a,b'] is
bounded &
['a,b'] c= dom f &
integral (
f,
a,
c)
= (integral (f,a,b)) + (integral (f,b,c)) )