let f, h, F be Function; for x being object holds (F [:] (f,x)) * h = F [:] ((f * h),x)
let x be object ; (F [:] (f,x)) * h = F [:] ((f * h),x)
dom ((dom f) --> x) = dom f
;
then A2:
dom (((dom f) --> x) * h) = dom (f * h)
by RELAT_1:163;
thus (F [:] (f,x)) * h =
(F .: (f,((dom f) --> x))) * h
.=
F .: ((f * h),(((dom f) --> x) * h))
by Th25
.=
F [:] ((f * h),x)
by A2, A3, Th11
; verum