let D, D9, E be non empty set ; for d being Element of D
for F being Function of [:D,D9:],E holds F [;] d,(<*> D9) = <*> E
let d be Element of D; for F being Function of [:D,D9:],E holds F [;] d,(<*> D9) = <*> E
let F be Function of [:D,D9:],E; F [;] d,(<*> D9) = <*> E
reconsider r = F [;] d,(<*> D9) as FinSequence of E by Th91;
len (<*> D9) = 0
;
then
len r = 0
by Th92;
hence
F [;] d,(<*> D9) = <*> E
; verum