423 questions
-1
votes
0
answers
56
views
SCIP make test do not give me .err file
I am trying to compare two algorithms in SCIP. To do this, I am following the steps in https://www.scipopt.org/scip/doc/html/TEST.php, but it says that SCIP automatically creates the scip/check/...
1
vote
1
answer
43
views
Manually controlling the iterations of optmize() function from pyscipopt
Is it possible to manually control the solving process of pyscipopt? I would like to repeatedly stop and resume the solving loop in a programmatic way.
This is what I've come up with so far:
m = Model(...
1
vote
1
answer
31
views
How can I access the entropy expression handler in the SCIP program?
According to the SCIP Optimization Suite 8.0 manual, SCIP contains an expression handler for the entropy function. I want to use it for the objective of my optimization program, but I don't understand ...
- 11
0
votes
1
answer
134
views
Unable to get dual values from SCIP solver
I have an LP that I am solving with SCIP. I have disabled all presolve settings (as far as I know) as I need the dual value of each constraint. However, when I use model.getDualsolLinear(i) to obtain ...
- 55
0
votes
0
answers
49
views
Using variables in forall and sum in Zimpl
I have the following ZIMPL code:
subto Restriction:
forall <a> in A:
sum <b> in B: parameter[b, a] <= 1;
When running SCIP, the result is infeasible. But if I add the b ...
- 360
2
votes
0
answers
57
views
Disabled Constraints in Branch-and-Price using SCIP
I am reaching out regarding an issue I’ve encountered in my branch-and-price implementation in SCIP. My implementation is based on the bin packing project, and I have made minimal modifications as my ...
- 21
0
votes
0
answers
40
views
Is there a way to pack scip into a self-contained, single executable program?
My server network connection is restricted so I want to compile locally and then upload to the server. But apparently scip has many dependencies, so I tried to pack it into an .AppImage file with ...
- 41
0
votes
0
answers
29
views
Understanding SCIPs subscips
I'm pretty new to the world of OR and SCIP and I'm having some trouble understanding the Subscip idea in SCIP or the example I'm referring to. I have a complex 2D cutting stock problem and I'm trying ...
- 3
0
votes
1
answer
167
views
Using Google OR-Tools with SCIP solver in x86 solution
I made a proof-of-concept application using Google OR-Tools with SCIP solver and it worked perfectly for my problem. But when I added OR-Tools to my actual solution (which uses .NET Framework 4.6.2), ...
- 77
1
vote
0
answers
40
views
Branching control in SCIP via Pyomo
I'm working on a "hard" scheduling problem that is currently written in Pyomo, and I'm using SCIP as the solver.
Since I know the structure of the problem, I understand that branching on ...
- 73
0
votes
0
answers
64
views
SCIP-SDP for solving mixed integer semidefinite programs
I have been looking at SCIP, specifically SCIP-SDP for solving a mixed semidefinite program - however I can't seem to find any examples on how I implement it in Python with PySCIPOpt.
Does anyone know ...
- 81
0
votes
1
answer
153
views
Obtain top N solutions in MIP problem using SCIP through OR-Tools
I would like to obtain more than one solution with SCIP. Using SAT (cp_model.CpModel()) I can collect all the possible solutions, but when they are too many, it takes way too long. I would like to be ...
- 472
2
votes
0
answers
113
views
Constraint Transformation in SCIP
I am using pyscipopt 4.3.0 (python 3.11.5; SCIP 9.0.0) to solve the following binary linear problem:
import pyscipopt as scip
_Name = "tiny_test"
m = scip.Model(_Name)
y1 = m.addVar(name=&...
- 31
1
vote
0
answers
61
views
issues with template <> during scip installation
I am trying to install scipoptsuite v6.0.1 (https://scipopt.org/download.php?fname=scipoptsuite-6.0.1.tgz) on my Mac M1. Following the instruction in the website:
Link to the changesoplex.cpp file: ...
0
votes
1
answer
247
views
ortools SCIP stuck in presolve
I'm using ortools to solve a Mixed-integer-problem, using SCIP as the solver.
And the solver.EnableOutput() is preformed, and the following output is displayed on my screen↓
(round 236, fast) ...
- 9
0
votes
2
answers
84
views
How to track the value of target function during ortools mixed-integer-programming solving process?
I'm using ortools SCIP to solve a really large mixed-integer-programming problem.
solver = pywraplp.Solver_CreateSolver('SCIP')
"""
Problem Definition Is Omitted Here
"""...
- 9
0
votes
0
answers
69
views
Exact tightened bounds in SCIP presolve?
In my current project, I want to make use of SCIP/PySCIPOpt to tighten the bounds of my system's variables given a number of constraints. However, it seems that the variable bounds after pre-computing ...
- 553
0
votes
3
answers
301
views
SCIP - stuck in clique table clean up
I'm running a multi year optimization with continuous and binary variables. For the 1st year, SCIP is able to pre-solve in 5 seconds and fully solve in under a minute, however, for the second year, ...
- 1
0
votes
1
answer
103
views
SCIP Column-Generation error: "pricing was aborted, but no branching could be created!"
I tried to run a Column-Generation program with SCIP, using the pricing call-back (a bit similar to the VRP example available online but on a relaxed/continuous Multi-Commodity Flow).
The program ...
- 21
0
votes
1
answer
102
views
get "Segmentation fault" when use pyscipopt addConsOr
I tried to use pyscipopt addConsOr but got Segmentation fault error. I want to add a constraint for two integers with x != y. If use
x = model.addVar("x", "I")
y = model....
- 1
0
votes
0
answers
482
views
Solve MINLP with SCIP
I'm using CVXPY with solver SCIP to solve mixed integer nonlinear programming problems (MINLPs). I have a problem with a constraint that contains log function. It means that if I comment that ...
- 63
2
votes
0
answers
387
views
How to warm start a LP problem in PySCIPOpt and initialize it with previous solution
I have a LP problem formulated in PySCIPOpt.
I would like to iteratively solve the LP, change the RHS of a specific constraint of this LP, solve it again, etc.
The goal would be to use information ...
0
votes
1
answer
104
views
Making SCIP for JNI and Or-Tools
Trying SCIP for the first time. Couldn't quite wrap my head around how to use JNI with SCIP version 8.x.x. on MacOs.
I downloaded scipoptsuite-8.0.4 from the website, then followed instruction of how ...
- 1,003
0
votes
1
answer
929
views
Could not build wheels for pyscipopt, which is required to install pyproject.toml-based projects
when installing a module for python, pyscipopt throws an error:
Collecting pyscipopt
Using cached PySCIPOpt-4.3.0.tar.gz (665 kB)
Installing build dependencies ... done
Getting requirements to ...
0
votes
1
answer
499
views
About the method of accelerating scip and parameter setting
About the method of accelerating scip and parameter setting
I want to improve the speed of the solution by setting some parameters, and I don't require the optimal solution, how can I get it quickly?
...
0
votes
1
answer
131
views
What does it mean in the output log in scip?
enter image description here
What does it mean in the output log in scip? Why some lines output node 1?
By using the command display display, I have already known the meaning of the parameters but I ...
0
votes
1
answer
168
views
Installation error for PySCIPOpt in vscode Mac Ventura OS
I am working on a Mixed Interger Linear Programming problem. I wanted to use SCIP solver to find the optimised solution for my problem. I was trying to install "PySCIPOpt" package in vscode ...
1
vote
0
answers
125
views
MPSolver callback misordered
I set callback of MPSolver<SCIP> but when debugging variables are out of bounds. I reduced test case and it seems variables are disordered, but it's still correct when output.
Problem is that it'...
- 1,177
0
votes
1
answer
427
views
SCIP Docker Image
Does anyone know of an SCIP docker image that also includes python 3.9+?
I have found this one, but it runs on python 3.7.
I basically need a docker image that can run this:
from pyomo.environ import ...
- 101
0
votes
1
answer
170
views
OSerror in using psycipopt in python
I wanted to use pyscipopt and I keep getting this error: OSError: [WinError 123] The filename, directory name, or volume label syntax is incorrect: 'C:\Program Files\SCIPOptSuite 8.0.3;D:\softwares\...
1
vote
1
answer
592
views
AWS Lambda Container works locally but fails when deployed
I wrote a python function for solving a Mixed Integer Linear Program, which uses the Pyomo Library and SCIP as external solver. My goal is to deploy the function as an AWS Lambda Function. Since I ...
- 21
0
votes
1
answer
94
views
What does BESTSOLFOUND mean in SCIP's callback?
I would like to understand the meaning of BESTSOLFOUND in the SCIP_EVENTTYPE_BESTSOLFOUND. I have tried to write a callback to execute this event handler that can be found here. By referring to the ...
- 193
-1
votes
1
answer
372
views
BESTSOLFOUND event handler on PySCIPopt
I am working on the problem in which I am willing to check and test some of the SCIP's event handlers. I see this SCIP document page and have some questions:
Do the event handlers callbacks return ...
- 193
0
votes
1
answer
659
views
How do I get all the optimal solutions from my linear programming with pyscipopt?
How do I get all the optimal solutions from my linear programming with pyscipopt?
I just want to display them(using print()).
I see that my Linear Programming has several optimal feasible solutions. ...
0
votes
1
answer
90
views
how do I convert constraints to standard form in pySCIPopt?
I'm loading MPS files into SCIP via pyscipopt. I would like to convert the constraints to standard form so that I can get a consistent tableau (via getLPBInvRow). I'm unsure on how to negate existing ...
- 5,422
0
votes
0
answers
96
views
SCIP Optimization Suite Installation: Vector Subscript Out of Range Error
I'm using Win10 and Visual Studio 2017. My SCIP Optimization Suite version is 8.0.3. I use CMake to compile to source code and is able to compile successfully:
However, when I tried to compile "...
- 87
0
votes
1
answer
493
views
How to rewrite MAX function for a constraint optimization problem in Python Pyomo SCIP?
I am trying to solve the following bin packing constraint optimization problem using Pyomo SCIP solver. Besides the objective of reducing the number of bins used for packing, I would also like to ...
- 33
0
votes
0
answers
124
views
Scip Branch and bound Pruning via bounds
In using the SCIP library I was wondering how exactly pruning is done with respect to the bounds.
If we consider a minimization problem we can instantiate by computing a lower bound via LP-relaxation ...
0
votes
1
answer
167
views
GetNNodes and GetTotalNodes SCIP
So I'm using the SCIP python package for B&B optimization. And I recently encountered the GetNNodes for a problem and GetTotalNodes and can't really decipher the difference from the documentation.
...
3
votes
2
answers
437
views
Multiple knapsack problem with no solution but finding a way to remove item(s) that are preventing a solution
I am trying to find a way to have as few boxes as possible that fit bags of chemicals. A box cannot have weight more than 3.3 kg but have to be higher than 2.7 kg. I came across Google's OR tools but ...
- 105
0
votes
1
answer
107
views
Dual solution, reduced cost, basic/non basic variable
I have following model:
NAME scip
OBJSENSE
MIN
ROWS
N Obj
G THISROW
L THATROW
L LASTROW
COLUMNS
COLONE Obj 1 THATROW 0.24
...
2
votes
1
answer
933
views
How to solve integer optimization problem with Python?
I have a system of linear equations Ax=b, A - matrix (m x n), x - (n x 1), b - (m x 1). The matrix A is almost all 0 and contains only ~ n*m^(1/2) non-zero elements. m and n can be quite large, such ...
- 23
2
votes
2
answers
1k
views
How to completeley disable presolve in scip
As the titles says, how can you completely disable presolve in scip.
I need this because otherwise SCIPgetDualSolVal and SCIPgetVarRedcost don't return be the (correct) values.
I tried the following ...
0
votes
1
answer
126
views
scip installation on Linux Server - Bliss failing
So I am about install the scipoptsuite 7.0.3 on a Linux Server, but get this weird error message.
/opt/scipoptsuite-7.0.3/scip/src/symmetry/compute_symmetry_bliss.cpp: In function ‘SCIP_RETCODE ...
- 13
0
votes
1
answer
395
views
Getting variable constraint value
How would I find the constraint value of a variable using SAT_INTEGER_PROGRAMMING given a feasible solution. Essentially solution_value() but for constraint.
Looked through documentation and nothing ...
- 33
0
votes
1
answer
55
views
Equivalent of xsum for pySCIPOpt
What is the equivalent of xsum from python Mip in pySCIPOpt to summarize arrays of variables in constraints?
- 2,283
2
votes
1
answer
995
views
Is the SCIP solver multi-threaded in PULP?
When I run the cord below at Jupyter-notebook,
solver = SCIP_CMD(path=scip_file, threads =7)
it returns the following error.
SCIP_CMD.__init__() got an unexpected keyword argument 'threads'
I ...
1
vote
2
answers
6k
views
How to install SCIP in python
I'm actually a .NET programmer (C#), and have not enough experience with Python, but recently had to work on a Python project involving Integer Optimization, and found SCIP a good option. I've tried ...
- 3,299
0
votes
1
answer
119
views
Passing SoPlex parameters to SCIP
I am using the SCIP solver in AMPL mode, with SoPlex as the LP solver. This is the pre-compiled version available at https://scipopt.org/index.php#download.
I am solving mixed integer programs (MIPs) ...
- 18.9k
0
votes
1
answer
164
views
SCIP: get sensitivity range of the objective function coefficient of a variable
I am implementing a branching rule in SCIP (using the C api). During the BRANCHEXECLP callback, I need to get the sensitivity range of the objective function coefficient of the candidates variables. ...
- 3