let i be Nat; :: thesis: for E, F, G being RealNormSpace
for Z being non empty Subset of [:E,F:]
for f being PartFunc of [:E,F:],G st f is_differentiable_on i + 1,Z holds
( f `partial`1| Z is_differentiable_on i,Z & f `partial`2| Z is_differentiable_on i,Z )

let E, F, G be RealNormSpace; :: thesis: for Z being non empty Subset of [:E,F:]
for f being PartFunc of [:E,F:],G st f is_differentiable_on i + 1,Z holds
( f `partial`1| Z is_differentiable_on i,Z & f `partial`2| Z is_differentiable_on i,Z )

let Z be non empty Subset of [:E,F:]; :: thesis: for f being PartFunc of [:E,F:],G st f is_differentiable_on i + 1,Z holds
( f `partial`1| Z is_differentiable_on i,Z & f `partial`2| Z is_differentiable_on i,Z )

let f be PartFunc of [:E,F:],G; :: thesis: ( f is_differentiable_on i + 1,Z implies ( f `partial`1| Z is_differentiable_on i,Z & f `partial`2| Z is_differentiable_on i,Z ) )
assume A1: f is_differentiable_on i + 1,Z ; :: thesis: ( f `partial`1| Z is_differentiable_on i,Z & f `partial`2| Z is_differentiable_on i,Z )
0 <= i by NAT_1:2;
then f is_differentiable_on 0 + 1,Z by A1, NDIFF_6:17, XREAL_1:7;
then A2: f is_differentiable_on Z by NDIFF_6:15, Th3;
then A3: ( f is_partial_differentiable_on`1 Z & f is_partial_differentiable_on`2 Z & ( for z being Point of [:E,F:] st z in Z holds
( ( for dx being Point of E holds ((f `partial`1| Z) /. z) . dx = ((f `| Z) /. z) . (dx,(0. F)) ) & ( for dy being Point of F holds ((f `partial`2| Z) /. z) . dy = ((f `| Z) /. z) . ((0. E),dy) ) ) ) ) by Th45;
A4: Z is open by A2, NDIFF_1:32;
set PD1 = f `partial`1| Z;
set PD2 = f `partial`2| Z;
A5: ( dom (f `partial`1| Z) = Z & dom (f `partial`2| Z) = Z ) by A3, NDIFF_7:def 10, NDIFF_7:def 11;
consider L10 being Lipschitzian LinearOperator of E,[:E,F:] such that
A6: for dx being Point of E holds L10 . dx = [dx,(0. F)] by Th46;
consider L20 being Lipschitzian LinearOperator of F,[:E,F:] such that
A7: for dy being Point of F holds L20 . dy = [(0. E),dy] by Th47;
set BL1 = R_NormSpace_of_BoundedLinearOperators (E,[:E,F:]);
set BL2 = R_NormSpace_of_BoundedLinearOperators (F,[:E,F:]);
A8: ( dom (Z --> L10) = Z & rng (Z --> L10) c= {L10} ) by FUNCOP_1:13;
L10 in the carrier of (R_NormSpace_of_BoundedLinearOperators (E,[:E,F:])) by LOPBAN_1:def 9;
then {L10} c= the carrier of (R_NormSpace_of_BoundedLinearOperators (E,[:E,F:])) by ZFMISC_1:31;
then A9: rng (Z --> L10) c= the carrier of (R_NormSpace_of_BoundedLinearOperators (E,[:E,F:])) by XBOOLE_1:1;
reconsider L1 = Z --> L10 as PartFunc of [:E,F:],(R_NormSpace_of_BoundedLinearOperators (E,[:E,F:])) by A8, A9, RELSET_1:4;
reconsider L100 = L10 as Point of (R_NormSpace_of_BoundedLinearOperators (E,[:E,F:])) by LOPBAN_1:def 9;
L1 = Z --> L100 ;
then A10: L1 is_differentiable_on i,Z by A4, Th50;
A11: for z being Point of [:E,F:] st z in Z holds
(f `partial`1| Z) /. z = ((f `| Z) /. z) * (L1 /. z)
proof
let z be Point of [:E,F:]; :: thesis: ( z in Z implies (f `partial`1| Z) /. z = ((f `| Z) /. z) * (L1 /. z) )
assume A12: z in Z ; :: thesis: (f `partial`1| Z) /. z = ((f `| Z) /. z) * (L1 /. z)
then A13: L1 /. z = L1 . z by A8, PARTFUN1:def 6
.= L10 by A12, FUNCOP_1:7 ;
reconsider H1 = (f `| Z) /. z as Lipschitzian LinearOperator of [:E,F:],G by LOPBAN_1:def 9;
reconsider H2 = L1 /. z as Lipschitzian LinearOperator of E,[:E,F:] by A13;
A14: (f `partial`1| Z) /. z is Lipschitzian LinearOperator of E,G by LOPBAN_1:def 9;
then A15: dom ((f `partial`1| Z) /. z) = the carrier of E by FUNCT_2:def 1;
A16: modetrans ((L1 /. z),E,[:E,F:]) = H2 by LOPBAN_1:def 11;
A17: dom (H1 * H2) = the carrier of E by FUNCT_2:def 1;
A18: for dx being object st dx in dom ((f `partial`1| Z) /. z) holds
((f `partial`1| Z) /. z) . dx = (H1 * H2) . dx
proof
let dx0 be object ; :: thesis: ( dx0 in dom ((f `partial`1| Z) /. z) implies ((f `partial`1| Z) /. z) . dx0 = (H1 * H2) . dx0 )
assume dx0 in dom ((f `partial`1| Z) /. z) ; :: thesis: ((f `partial`1| Z) /. z) . dx0 = (H1 * H2) . dx0
then reconsider dx = dx0 as Point of E by A14, FUNCT_2:def 1;
A19: dom L10 = the carrier of E by FUNCT_2:def 1;
thus ((f `partial`1| Z) /. z) . dx0 = ((f `| Z) /. z) . (dx,(0. F)) by A2, A12, Th45
.= ((f `| Z) /. z) . [dx,(0. F)] by BINOP_1:def 1
.= ((f `| Z) /. z) . (L10 . dx) by A6
.= (H1 * H2) . dx0 by A13, A19, FUNCT_1:13 ; :: thesis: verum
end;
(f `partial`1| Z) /. z = H1 * H2 by A15, A17, A18, FUNCT_1:2;
hence (f `partial`1| Z) /. z = ((f `| Z) /. z) * (L1 /. z) by A16, LOPBAN_1:def 11; :: thesis: verum
end;
A20: f `| Z is_differentiable_on i,Z by A1, Th36;
consider B being Lipschitzian BilinearOperator of (R_NormSpace_of_BoundedLinearOperators (E,[:E,F:])),(R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)),(R_NormSpace_of_BoundedLinearOperators (E,G)) such that
A21: for u being Point of (R_NormSpace_of_BoundedLinearOperators (E,[:E,F:]))
for v being Point of (R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)) holds B . (u,v) = v * u by Th38;
set w2 = <:L1,(f `| Z):>;
A22: dom <:L1,(f `| Z):> = (dom (f `| Z)) /\ (dom L1) by FUNCT_3:def 7
.= Z /\ (dom L1) by A2, NDIFF_1:def 9
.= Z by A8 ;
A23: rng <:L1,(f `| Z):> c= [:(rng L1),(rng (f `| Z)):] by FUNCT_3:51;
[:(rng L1),(rng (f `| Z)):] c= [: the carrier of (R_NormSpace_of_BoundedLinearOperators (E,[:E,F:])), the carrier of (R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)):] by ZFMISC_1:96;
then rng <:L1,(f `| Z):> c= the carrier of [:(R_NormSpace_of_BoundedLinearOperators (E,[:E,F:])),(R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)):] by A23, XBOOLE_1:1;
then reconsider w2 = <:L1,(f `| Z):> as PartFunc of [:E,F:],[:(R_NormSpace_of_BoundedLinearOperators (E,[:E,F:])),(R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)):] by RELSET_1:4, A22;
reconsider W = B * w2 as PartFunc of [:E,F:],(R_NormSpace_of_BoundedLinearOperators (E,G)) ;
A24: W is_differentiable_on i,Z by A10, A20, Th39;
dom B = the carrier of [:(R_NormSpace_of_BoundedLinearOperators (E,[:E,F:])),(R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)):] by FUNCT_2:def 1;
then rng w2 c= dom B ;
then A25: dom W = Z by A22, RELAT_1:27;
for x0 being object st x0 in dom (f `partial`1| Z) holds
(f `partial`1| Z) . x0 = W . x0
proof
let x0 be object ; :: thesis: ( x0 in dom (f `partial`1| Z) implies (f `partial`1| Z) . x0 = W . x0 )
assume A26: x0 in dom (f `partial`1| Z) ; :: thesis: (f `partial`1| Z) . x0 = W . x0
then reconsider x = x0 as Point of [:E,F:] ;
A27: (f `partial`1| Z) . x0 = (f `partial`1| Z) /. x by A26, PARTFUN1:def 6
.= ((f `| Z) /. x) * (L1 /. x) by A11, A26, A5
.= B . ((L1 /. x),((f `| Z) /. x)) by A21
.= B . [(L1 /. x),((f `| Z) /. x)] by BINOP_1:def 1 ;
A28: dom (f `| Z) = Z by A2, NDIFF_1:def 9;
A29: dom <:L1,(f `| Z):> = (dom L1) /\ (dom (f `| Z)) by FUNCT_3:def 7
.= Z by A8, A28 ;
[(L1 /. x),((f `| Z) /. x)] = [(L1 . x),((f `| Z) /. x)] by A5, A8, A26, PARTFUN1:def 6
.= [(L1 . x),((f `| Z) . x)] by A5, A26, A28, PARTFUN1:def 6
.= w2 . x by A5, A26, A29, FUNCT_3:def 7 ;
hence (f `partial`1| Z) . x0 = W . x0 by A5, A26, A27, A29, FUNCT_1:13; :: thesis: verum
end;
hence f `partial`1| Z is_differentiable_on i,Z by A5, A24, A25, FUNCT_1:2; :: thesis: f `partial`2| Z is_differentiable_on i,Z
A30: ( dom (Z --> L20) = Z & rng (Z --> L20) c= {L20} ) by FUNCOP_1:13;
L20 in the carrier of (R_NormSpace_of_BoundedLinearOperators (F,[:E,F:])) by LOPBAN_1:def 9;
then {L20} c= the carrier of (R_NormSpace_of_BoundedLinearOperators (F,[:E,F:])) by ZFMISC_1:31;
then A31: rng (Z --> L20) c= the carrier of (R_NormSpace_of_BoundedLinearOperators (F,[:E,F:])) by XBOOLE_1:1;
reconsider L2 = Z --> L20 as PartFunc of [:E,F:],(R_NormSpace_of_BoundedLinearOperators (F,[:E,F:])) by A30, A31, RELSET_1:4;
reconsider L100 = L20 as Point of (R_NormSpace_of_BoundedLinearOperators (F,[:E,F:])) by LOPBAN_1:def 9;
L2 = Z --> L100 ;
then A32: L2 is_differentiable_on i,Z by A4, Th50;
A33: ( dom (Z --> L20) = Z & rng (Z --> L20) c= {L20} ) by FUNCOP_1:13;
A34: for z being Point of [:E,F:] st z in Z holds
(f `partial`2| Z) /. z = ((f `| Z) /. z) * (L2 /. z)
proof
let z be Point of [:E,F:]; :: thesis: ( z in Z implies (f `partial`2| Z) /. z = ((f `| Z) /. z) * (L2 /. z) )
assume A35: z in Z ; :: thesis: (f `partial`2| Z) /. z = ((f `| Z) /. z) * (L2 /. z)
then A36: L2 /. z = L2 . z by A33, PARTFUN1:def 6
.= L20 by A35, FUNCOP_1:7 ;
reconsider H1 = (f `| Z) /. z as Lipschitzian LinearOperator of [:E,F:],G by LOPBAN_1:def 9;
reconsider H2 = L2 /. z as Lipschitzian LinearOperator of F,[:E,F:] by A36;
A37: (f `partial`2| Z) /. z is Lipschitzian LinearOperator of F,G by LOPBAN_1:def 9;
then A38: dom ((f `partial`2| Z) /. z) = the carrier of F by FUNCT_2:def 1;
A39: modetrans ((L2 /. z),F,[:E,F:]) = H2 by LOPBAN_1:def 11;
A40: dom (H1 * H2) = the carrier of F by FUNCT_2:def 1;
A41: for dx being object st dx in dom ((f `partial`2| Z) /. z) holds
((f `partial`2| Z) /. z) . dx = (H1 * H2) . dx
proof
let dx0 be object ; :: thesis: ( dx0 in dom ((f `partial`2| Z) /. z) implies ((f `partial`2| Z) /. z) . dx0 = (H1 * H2) . dx0 )
assume dx0 in dom ((f `partial`2| Z) /. z) ; :: thesis: ((f `partial`2| Z) /. z) . dx0 = (H1 * H2) . dx0
then reconsider dx = dx0 as Point of F by A37, FUNCT_2:def 1;
A42: dom L20 = the carrier of F by FUNCT_2:def 1;
thus ((f `partial`2| Z) /. z) . dx0 = ((f `| Z) /. z) . ((0. E),dx) by A2, A35, Th45
.= ((f `| Z) /. z) . [(0. E),dx] by BINOP_1:def 1
.= ((f `| Z) /. z) . (L20 . dx) by A7
.= (H1 * H2) . dx0 by A36, A42, FUNCT_1:13 ; :: thesis: verum
end;
(f `partial`2| Z) /. z = H1 * H2 by A38, A40, A41, FUNCT_1:2;
hence (f `partial`2| Z) /. z = ((f `| Z) /. z) * (L2 /. z) by A39, LOPBAN_1:def 11; :: thesis: verum
end;
A43: f `| Z is_differentiable_on i,Z by A1, Th36;
consider B being Lipschitzian BilinearOperator of (R_NormSpace_of_BoundedLinearOperators (F,[:E,F:])),(R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)),(R_NormSpace_of_BoundedLinearOperators (F,G)) such that
A44: for u being Point of (R_NormSpace_of_BoundedLinearOperators (F,[:E,F:]))
for v being Point of (R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)) holds B . (u,v) = v * u by Th38;
set w2 = <:L2,(f `| Z):>;
A45: dom <:L2,(f `| Z):> = (dom (f `| Z)) /\ (dom L2) by FUNCT_3:def 7
.= Z /\ (dom L2) by A2, NDIFF_1:def 9
.= Z by A33 ;
A46: rng <:L2,(f `| Z):> c= [:(rng L2),(rng (f `| Z)):] by FUNCT_3:51;
[:(rng L2),(rng (f `| Z)):] c= [: the carrier of (R_NormSpace_of_BoundedLinearOperators (F,[:E,F:])), the carrier of (R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)):] by ZFMISC_1:96;
then rng <:L2,(f `| Z):> c= the carrier of [:(R_NormSpace_of_BoundedLinearOperators (F,[:E,F:])),(R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)):] by A46, XBOOLE_1:1;
then reconsider w2 = <:L2,(f `| Z):> as PartFunc of [:E,F:],[:(R_NormSpace_of_BoundedLinearOperators (F,[:E,F:])),(R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)):] by A45, RELSET_1:4;
reconsider W = B * w2 as PartFunc of [:E,F:],(R_NormSpace_of_BoundedLinearOperators (F,G)) ;
dom B = the carrier of [:(R_NormSpace_of_BoundedLinearOperators (F,[:E,F:])),(R_NormSpace_of_BoundedLinearOperators ([:E,F:],G)):] by FUNCT_2:def 1;
then rng w2 c= dom B ;
then A47: dom W = Z by A45, RELAT_1:27;
for x0 being object st x0 in dom (f `partial`2| Z) holds
(f `partial`2| Z) . x0 = W . x0
proof
let x0 be object ; :: thesis: ( x0 in dom (f `partial`2| Z) implies (f `partial`2| Z) . x0 = W . x0 )
assume A48: x0 in dom (f `partial`2| Z) ; :: thesis: (f `partial`2| Z) . x0 = W . x0
then reconsider x = x0 as Point of [:E,F:] ;
A49: (f `partial`2| Z) . x0 = (f `partial`2| Z) /. x by A48, PARTFUN1:def 6
.= ((f `| Z) /. x) * (L2 /. x) by A5, A34, A48
.= B . ((L2 /. x),((f `| Z) /. x)) by A44
.= B . [(L2 /. x),((f `| Z) /. x)] by BINOP_1:def 1 ;
A50: dom (f `| Z) = Z by A2, NDIFF_1:def 9;
A51: dom <:L2,(f `| Z):> = (dom L2) /\ (dom (f `| Z)) by FUNCT_3:def 7
.= Z by A33, A50 ;
[(L2 /. x),((f `| Z) /. x)] = [(L2 . x),((f `| Z) /. x)] by A5, A33, A48, PARTFUN1:def 6
.= [(L2 . x),((f `| Z) . x)] by A5, A48, A50, PARTFUN1:def 6
.= w2 . x by A5, A48, A51, FUNCT_3:def 7 ;
hence (f `partial`2| Z) . x0 = W . x0 by A5, A48, A49, A51, FUNCT_1:13; :: thesis: verum
end;
then f `partial`2| Z = W by A5, A47, FUNCT_1:2;
hence f `partial`2| Z is_differentiable_on i,Z by A32, A43, Th39; :: thesis: verum