Is it possible in general to reduce number of variables of multi-variable real-to-real function by converting it to complex-to-real function, for example $g=f(a_1,a_2,a_3,a_4)$ in to $h=w(b_1,b_2)$? How to do it?
Update: Is it possible to two variable real-to-real function? How to obtain the formula?