theorem Th58: :: NDIFF13:57
for S, E, F being RealNormSpace
for u being PartFunc of S,E
for v being PartFunc of S,F
for w being PartFunc of S,[:E,F:]
for Z being Subset of S st w = <:u,v:> & u is_differentiable_on Z & v is_differentiable_on Z holds
( diff (w,0,Z) is_differentiable_on Z & ex T being Lipschitzian LinearOperator of [:(diff_SP (1,S,E)),(diff_SP (1,S,F)):],(diff_SP (1,S,[:E,F:])) st
( T = CTP (S,(diff_SP (0,S,E)),(diff_SP (0,S,F))) & diff (w,1,Z) = T * <:(diff (u,1,Z)),(diff (v,1,Z)):> ) )