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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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How to make SCIP use the LAPACK library?

I have built a MINLP model in Pyomo in Linux system and I used SCIP to solve the model. Then I encountered the problem shown below. enter image description here Then SCIP starts optimization and takes a large amount of time. I googled the problem…
Qianqian
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SCIP: Children vs Parent vs Siblings

I am implementing a node selector. I was thinking that SCIPgetLeaves will give me the list of current nodes among which one needs to be selected for further branching. After the presolving stage, SCIPgetLeaves in NODESELSELECT() doesn't return any…
pg2455
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std priority and memsave priority in SCIP node selectors

I noticed that there are two types of priorities in : memsave prio and std priority. When does it switch between the two? Is there a threshold parameter that can be set to influence this switching?
pg2455
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Solving the MIP at a node with same parameters as the root node

In the branch-and-cut framework of SCIP, is it possible to solve a particular node of the tree with the same parameters (like presolving, restarts, etc.) as root node? I want to get better bounds for particular nodes, and I think treating the…
pg2455
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Dynamically changing SCIP parameters

I want to dynamically change the parameters related to cut generation and primal heuristics depending on the state of the solving process. It doesn't give me an error when I set parameters like maxrounds after the branching on a particular node, but…
pg2455
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What do the events that `SCIP_EVENTTYPE_NODESOLVED` comprises mean?

I'm trying to catch a change in the dual bound using an event handler. There is no event in type_event.h for catching this, so I want to use the SCIP_EVENTTYPE_NODEFEASIBLE event. I'm a bit confused by the relationship between the events that…
rocarvaj
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Dual bound change event type?

I'm trying to code a simple event handler that does certain things whenever the best primal or dual bounds change (please let me know if I'm reinventing the wheel here and there is already a way of doing this). For the primal bound I can catch the…
rocarvaj
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Cannot understand the reason of the problem being infeasible

I have a simple linear programming problem written in OSiL format, which is carved out from a complicated non-linear problem that reported as infeasible by SCIP. This simple problem is the minimal lines to reproduce this infeasible problem, however…
Bin Tang
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How to index set of subsets in ZIMPL?

Given S as a set of subsets, I'd like to print it out, and index it: set S[]:=subsets({1..5}, 3); do forall in S do print S[i]; # Neither does the following work: do print S; I get the following error: Reading debug.zpl *** Error 142:…
Nemo
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Limiting the soIving time using PySCIPOpt (SCIP ILP optimization for Python)

I am using PySCIPOpt which is a Python library for the SCIP ILP solver. I would like to limit the optimization time. I found in the SCIP documentation that this can be done using SCIPsetRealParam(scip, "limits/time", 600). But how can this be done…
Benoît Châtelain
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Trouble figuring out how to use SCIP in Java on Windows (with eclipse)

I'm trying to set up the SCIP optimization solver https://scip.zib.de/index.php I use Windows and prefer Java with eclipse. I see there is a Java wrapper and example files, e.g.,…
beserious
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SCIP how to add objective function in my source code by using c++ when I use SCIP

I want to use SCIP as a MIP solver, but I do not know how to add objective function in my source code. I did not find related code in SCIP C++ example code.
K.wang
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GCG/ Error: Calling hmetis unsuccessful! happen during the process of 'optimize'

I installed the GCG and built the soft link with hMETIS in the scipoptsuite/gcg directory: ubuntu18:~/Documents/Software/scipoptsuite-6.0.0/gcg$ ln -s /home/yang/Documents/Software/scipoptsuite-6.0.0/hmetis-2.0pre1/Linux-x86_64/hmetis2.0pre1…
Qidong
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SoPlex yields wrong answer

I have an LP in CPLEX LP format, in file LP.tmp Maximize obj: x0 + 2 x1 + 3 x2 + 4 x3 + 5 x4 + 7 x5 Subject To c0: 1 x0 + 1 x1 + 1 x2 + 1 x3 + 1 x4 + 1 x5 + 1 x6 + 1 x7 + 1 x8 = 0 End On this I call soplex -X -x -o0 -f0 -v3 LP.tmp This is…
Hennich
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What is the 'libzimpl-NOTFOUND' Error that occurs during the installation of SCIP

I want to run GCG thus I downloaded the scipoptsuite-6.0.0.tgz and did tar xvzf scipoptsuite-6.0.0.tgz in Ubuntu/Linux. I replaced some documents with the second patch files scipoptsuite-6.0.0_patch01.tgz. Then I configured the build: `cmake…
Qidong
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