theorem Th10: :: CAT_7:10

for C1, C2, C3, C4 being category
for F being Functor of C1,C2
for G being Functor of C2,C3
for H being Functor of C3,C4 st F is covariant & G is covariant & H is covariant holds
H (*) (G (*) F) = (H (*) G) (*) F