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Questions tagged [scip]

Software package for solving mixed integer linear and nonlinear programming problems and part of the SCIP Optimization Suite. SCIP is distributed under the Apache 2.0 license and its C source code is available.

Mixed integer programming is the task to optimize a linear functional over a polyhedron, where some or all variables are constrained to be integer. The SCIP Optimization suite offers a branch-and-cut implementation, and a standalone implementation of the Simplex algorithm, called SoPlex, to solve linear programming problems.

Furthermore, SCIP comes with a modelling language ZIMPL that aims to ease the task of formulating mixed integer programming problems, a parallel solver called UG, and an implementation of the branch-and-cut-and-price algorithm called GCG.

The SCIP Optimization suite is one of the fastest implementations whose source code is available. It is written in C, but also offers a C++ interface.

<= 03.11.2022:
  • SCIP is free for academic research and can be licensed for commercial use.
>= 04.11.2022:
  • SCIP (as well as SoPlex) is distributed under the Apache 2.0 license.
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Eliminating subtours in a simple TSP problem

I am trying to solve a very simple TSP problem but the TSP example of SCIP is a bit intimidating. I just want to add simple Lazy constraints like how GuRoBi does. I might need some help in understanding what is happening at some places. I assume I…
Morpheus
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SCIP Optimization of an Exponential Function

I am having issues summing over an exponential equation and using this as is the objective function. I have also tried writing the exponential equation in as a constraint as I thought that may be another method to solve this issue, but this did not…
jdw
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Deleting SCIP constraints

I'm trying to look for the constraint that causes infeasible solution. For that I'm applying delCons() method of the SCIP model, which throughs me an segfault error. I'm using pyscipopt wrapper for python. The issue is: how to delete constraints if…
eugene
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How to get list of non-zero variables in scip

I'm using pyscipopt to use scip and in my model I want to look at those columns of a matrix that correspond to the variables that are non-zero. However the expression A[:, np.nonzero(var_list)[0]] doesn't work as expected because the objects in the…
yagod
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How can I set scip options using pyomo?

I am trying to set parameter values for solving a pyomo model using SCIP. When I run opt = SolverFactory('scipampl') solver_message = opt.solve(model, tee=True) SCIP solves the model mich means that the setup of scipampl has worked. Yet I'm not…
Christoph Neumann
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undefined reference to `SCIPcreate' and more

I am trying to use scip package to solve vrp example but when i want to use ctrl+shift+B to build task, i encountered with this error /tmp/ccu9Xcmg.o: In function execmain(int, char**): /home/fahime/Desktop/VRP/src/main_vrp.cpp:294: undefined…
fahime nazari
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Are regular functions in SCIP callable in PySCIPOpt?

I am currently using SCIP in a Linux environment and would like to move towards using PySCIPOpt as my research is slowly moving towards Machine Learning. I have read the PySCIPOpt tutorial in Github as well as a document by S Maher and found them…
Chia Teck Yan
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adding a NOT-constraint in pyscipopt

I'd like to add a NOT-constraint to my PySCIPOpt model. I can see andConsAnd, addConsOr and addConsXor but there isn't one for the NOT operator. What would be the easiest way to add a NOT-constraint? I came up with: x = model.addVar('B') not_x =…
Jacek
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makefile example to use soplex

I'm trying to link soplex (the infinite precision LP solver of SCIP) in my C/C++ code. I managed to install soplex in my linux machine and from the command line it works. My problem is that I do not manage to link it in my code: I'm currently using…
fabio
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Is there a way to set the time limit for branch and bound in SCIP?

I was wondering if there is a way to set the upper bound of the time taken to solve a MILP problem but only on the branch and bound time. I was able to find a parameter for the total running time but I am unable to find the parameter that restricts…
Morpheus
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Adding constraints to nodes in PySCIPOpt

I'm using the Python Interface of SCIP (PySCIPOpt) to write a custom branching rule. As far as I understood from reading the documentation, a good way to do this is making use of the methods self.model.createChild and self.model.addConsNode. So I…
CharJ
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Understanding the display output in SCIP and branch-and-cut mechanism

I am trying to understand the meaning of the display output when using SCIP to solve an MILP using Branch-and-cut code. I use the TSP example as a reference. time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts…
Morpheus
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Indicator Variable in PySCIPOpt

Using pyscipopt in python I have set up a continuous variable and binary variable: For j in J: x[j] = model.addVar(vtype="C", name="x(%s)"%j) y[j] = model.addVar(vtype="B", name="y(%s)"%j) What I am trying to do is get a simple indicator…
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How to print variable names in SCIP?

I am trying to print out variable names and their reliable pseudocost scores. This is because I am trying an experiment of using the reliable pseudocost scores of all the candidate variables as an initialisation of another algorithm. My input is a…
Chia Teck Yan
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Is it possible to retain information after solving a problem and reusing the same information to solve the same problem but with different settings?

My problems are large SAT problems. In SCIP7.0.0, there are many branching rules to choose from. If I send in a problem to SCIP and SCIP solves the problem, is it possible to use the learnt information throughout the solving process, say cutting…
Chia Teck Yan
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