# Surplus variable

In an inequality constraint of the form $LaTeX: \textstyle g(x) \ge b,$ the level of surplus is $LaTeX: g(x)-b,$ which is designated by the surplus variable, $LaTeX: s.$ Then, the original constraint is equivalent to the defining equation, $LaTeX: g(x) - s = b,$ plus the non-negativity, $LaTeX: s \ge 0.$