theorem :: INTEGR24:27

for f being PartFunc of REAL,REAL
for a, b being Real st [.a,b.[ c= dom f & f is_right_ext_Riemann_integrable_on a,b holds
for c, d being Real st a <= c & c < d & d < b holds
( f is_left_ext_Riemann_integrable_on c,d & ext_left_integral (f,c,d) = integral (f,c,d) )