let f be PartFunc of (REAL 2),REAL ; :: thesis: for z0 being Element of REAL 2
for N being Neighbourhood of (proj 1,2) . z0 st f is_hpartial_differentiable`11_in z0 & N c= dom (SVF1 1,(pdiff1 f,1),z0) holds
for h being convergent_to_0 Real_Sequence
for c being V8() Real_Sequence st rng c = {((proj 1,2) . z0)} & rng (h + c) c= N holds
( (h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c)) is convergent & hpartdiff11 f,z0 = lim ((h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c))) )
let z0 be Element of REAL 2; :: thesis: for N being Neighbourhood of (proj 1,2) . z0 st f is_hpartial_differentiable`11_in z0 & N c= dom (SVF1 1,(pdiff1 f,1),z0) holds
for h being convergent_to_0 Real_Sequence
for c being V8() Real_Sequence st rng c = {((proj 1,2) . z0)} & rng (h + c) c= N holds
( (h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c)) is convergent & hpartdiff11 f,z0 = lim ((h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c))) )
let N be Neighbourhood of (proj 1,2) . z0; :: thesis: ( f is_hpartial_differentiable`11_in z0 & N c= dom (SVF1 1,(pdiff1 f,1),z0) implies for h being convergent_to_0 Real_Sequence
for c being V8() Real_Sequence st rng c = {((proj 1,2) . z0)} & rng (h + c) c= N holds
( (h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c)) is convergent & hpartdiff11 f,z0 = lim ((h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c))) ) )
assume A1: ( f is_hpartial_differentiable`11_in z0 & N c= dom (SVF1 1,(pdiff1 f,1),z0) ) ; :: thesis: for h being convergent_to_0 Real_Sequence
for c being V8() Real_Sequence st rng c = {((proj 1,2) . z0)} & rng (h + c) c= N holds
( (h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c)) is convergent & hpartdiff11 f,z0 = lim ((h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c))) )
let h be convergent_to_0 Real_Sequence; :: thesis: for c being V8() Real_Sequence st rng c = {((proj 1,2) . z0)} & rng (h + c) c= N holds
( (h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c)) is convergent & hpartdiff11 f,z0 = lim ((h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c))) )
let c be V8() Real_Sequence; :: thesis: ( rng c = {((proj 1,2) . z0)} & rng (h + c) c= N implies ( (h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c)) is convergent & hpartdiff11 f,z0 = lim ((h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c))) ) )
assume A2: ( rng c = {((proj 1,2) . z0)} & rng (h + c) c= N ) ; :: thesis: ( (h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c)) is convergent & hpartdiff11 f,z0 = lim ((h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c))) )
A3: pdiff1 f,1 is_partial_differentiable_in z0,1 by A1, Th9;
consider x0, y0 being Real such that
A4: z0 = <*x0,y0*> by FINSEQ_2:120;
partdiff (pdiff1 f,1),z0,1 = diff (SVF1 1,(pdiff1 f,1),z0),x0 by A3, A4, PDIFF_2:13
.= hpartdiff11 f,z0 by A1, A4, Th5 ;
hence ( (h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c)) is convergent & hpartdiff11 f,z0 = lim ((h " ) (#) (((SVF1 1,(pdiff1 f,1),z0) /* (h + c)) - ((SVF1 1,(pdiff1 f,1),z0) /* c))) ) by A1, A2, A3, PDIFF_2:17; :: thesis: verum