I use MIPOptimizer to do integer linear program. For that program. there are two solutions, so how can I get these two solutions? The code is like this in java: MIPOptimizer opt = new MIPOptimizer("integer linear program"); opt.addVariableDiscrete("x1", 1.0, 0, 100); opt.addVariableDiscrete("x2", 1.0, 0, 70); opt.addConstraint("-x1 + 12x2 <= 24"); opt.addConstraint("18x1 + 7x2 <= 66"); opt.addObjective("x1 + x2"); opt.maximize(); ..... I can only get one solution (x1=3,x2=1),but there is another (x1=2,x2=2). So how can get another? Futher, I want to get another by add addition constraints that is MIPOptimizer opt = new MIPOptimizer("integer linear program"); opt.addVariableDiscrete("x1", 1.0, 0, 100); opt.addVariableDiscrete("x2", 1.0, 0, 70); opt.addConstraint("-x1 + 12x2 <= 24"); opt.addConstraint("18x1 + 7x2 <= 66"); opt.addConstraint("x1!= 3"); opt.addConstraint("x2 != 1"); opt.addObjective("x1 + x2"); opt.maximize(); ... There is a runing exception when I run the above code with the additional constraints. "error in constraint equation" So, what should i do to express the additional constraints? Thanks