Questions tagged [presolve-preprocessing]

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SCIP do not branch

I am trying to solve Nurse scheduling problem using SCIP. The SCIP solve it in pre-solving stage itself and gives optimal solution. I don't want that to happen., because I want to use the branching ...
505 views

Good references for reduced cost fixing?

Reduced cost fixing is a technique used by mixed integer programming (MIP) solvers to safely fix variables to certain values. While this technique is well-known among the MIP community, I don't know ...
194 views

Standard Form for LP and MPS

Is there any way I could have Gurobi/CPLEX or any other package write/export MPS and LP files in the standard LP construct loaded with slack variables and transformations required for unsigned vars? ...
• 394
869 views

Do LP solvers convert LPs to standard form?

To solve a linear program (LP) using the simplex method one first needs to bring the LP to standard form. This requires replacing every equality constraint with two inequalities and replacing every ...
• 2,305
305 views

Objective Integrality Cuts

Consider a mixed integer linear program with an objective function that includes only integer variables. Objective integrality cuts are known as a class of valid inequalities that can be added to ...
• 2,140
220 views

Obtaining the system of irredundant inequalities from a set of inequalities using CPLEX

Given a linear system of inequalities $Ax \geq b$, I would ideally like to compute the irredundant set for those set of inequalities. I know how to do so mathematically, but I was wondering if there ...
• 1,458
212 views

How to detect unbounded problems

How can I algorithmically detect whether an (MI)NLP problem is unbounded or not? Finding a source for this has proven tricky, because people in the literature seem to talk a lot about what to do if ...
• 11.9k