answered 28 May '12, 08:14 fbahr ♦ 1
If z occurs nowhere else, replace zy with a new variable u and it is linear. If z does appear elsewhere, substitution will not help, and the equation is quadratic (better than rational, but not linear).
(28 May '12, 15:13)
Paul Rubin ♦♦
@Paul: Following AIMMS Modeling Guide, the product of two continuous variables, \(x_1 \cdot x_2\), can be converted into a separable form:
(28 May '12, 16:05)
fbahr ♦
1
@Florian: Okay. I've seen the differenceofsquares trick before, but (as you note) while it can be approximated with piecewise linear functions, it's not truly linear. TANSTAAFL.
(28 May '12, 16:39)
Paul Rubin ♦♦

What types are (x) and (y) (continuous, integer, or binary)?