let f be PartFunc of (REAL 3),REAL ; for u0 being Element of REAL 3 st f is_hpartial_differentiable`32_in u0 holds
SVF1 2,(pdiff1 f,3),u0 is_continuous_in (proj 2,3) . u0
let u0 be Element of REAL 3; ( f is_hpartial_differentiable`32_in u0 implies SVF1 2,(pdiff1 f,3),u0 is_continuous_in (proj 2,3) . u0 )
assume
f is_hpartial_differentiable`32_in u0
; SVF1 2,(pdiff1 f,3),u0 is_continuous_in (proj 2,3) . u0
then
pdiff1 f,3 is_partial_differentiable_in u0,2
by Th12ForSecondOrder;
hence
SVF1 2,(pdiff1 f,3),u0 is_continuous_in (proj 2,3) . u0
by PDIFF_4:32; verum