for f being PartFunc of REAL,REAL
for a, b being Real st f is_left_improper_integrable_on a,b & left_improper_integral (f,a,b) = -infty holds
for Intf being PartFunc of REAL,REAL st dom Intf = ].a,b.] & ( for x being Real st x in dom Intf holds
Intf . x = integral (f,x,b) ) holds
Intf is_right_divergent_to-infty_in a