the constraints themselves, one of the many uses of Big M, for example, refers to ensuring equality of variables only when a certain binary variable takes on one value, but to leave the variables "open" if the binary variable takes on its opposite value. One instance of this is as follows: for a sufficiently large M and z binary variable (0 or 1), the constraints ensure that when then . Otherwise, when , then , indicating that the variables x and y can have any values so long as the absolute value of their difference is bounded by (hence the need for M to be "large enough.") See also Two phase method (linear programming) another approach for solving problems with >= constraints Karush–Kuhn–Tucker conditions, which apply to Non-Linear Optimization problems with inequality constraints. References and external links Bibliography Discussion Simplex – Big M Method, Lynn Killen, Dublin City University. The Big M Method, businessmanagementcourses.org The Big M Method, Mark Hutchinson The Big-M Method with the Numerical Infinite M, a recently introduced parameterless variant A THREE-PHASE SIMPLEX METHOD FOR INFEASIBLE AND UNBOUNDED LINEAR PROGRAMMING PROBLEMS, Big M method for M=1 Linear programming Linear algebra