Questions tagged [or-tools]
Questions related to or-tools, Google's open-source software suite for optimization
135
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OR-Tools CP-SAT solver: is it possible to name a constraint like in GUROBI
I try to implement cp model with OR-tools CP-SAT solver. Please, is it possible to name constraints for being able to manage conflict later like for variables:
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58
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How to cmpute IIS using the Or-Tools solver?
I'm trying to solve a MIP using Google Or-Tools, but it's showing that the model is infeasible. I'd like to know if there is a convenient way to analyze which constraint or variable bounds are causing ...
- 69
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37
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Output a readable model file and control the solver parameters in Or-Tools
I am using Java to call the API of or-tools in IntelliJ IDEA to solve a mixed-integer programming problem. There are some modeling statements such as ...
- 69
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50
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Machine-state constraints for jobshop problem
Problem outline
I am trying to implement a job-shop problem using OR-Tools, which can be framed as a typical job-shop problem (minimize overall maketime of machines performing tasks) but the ...
1
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1
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68
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Non integer linear objective in or-tools CP-SAT
It seems that or-tools' CP-SAT solvers allows for non-integer coefficients in a linear objective expression. Am I correct, or is it just that the solver doesn't check for integrity and rounds the ...
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67
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Scheduling repeated tasks with minimum duty cycles
Several tasks need to run repeatedly in a channel, one at a time, over a repeating time frame of length $T$. Associated to each task $i$ is the duration $L_i$ the task will take to run, and a maximum ...
- 111
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2
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60
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Formulating assignment problem with people attributes that need to be balanced per assignment attribute in or-tools, CP-sat
I'm trying to do an assignment problem with the following characteristics:
I have two sets that need to be matched with each other, set A (Students) and set B (Class combinations). Set A and B have ...
- 21
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1
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88
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Using binary variable or integer variable in Constraint Programming (CP)?
I am trying to solve an assignment problem by Constraint Programming (CP). Let us consider a task assignment problem that have $|M|$ tasks and $|N|$ machines, each task has different processing time ...
- 700
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40
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Adding synchronisation constraint in Prize-collecting VRPTW
I am solving a Prize Collecting VRPTW. In my problem, each node represents a visit that needs to be made within a certain time window, and the "prize" for each node is the time spent at the ...
- 33
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1
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103
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Team Orienteering Problem with Time Windows infeasible using CP-SAT solver in Google OR-Tool
I am developing a TOPTW where there are a set of N nodes. Each node i is associated with a visit time, which is also the score Si. The starting point and the end point of each tour is fixed, which is ...
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75
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Are there any hidden differences in OR-Tools' default parameters for a MIP model in Python vs C++?
or-tools-discuss cross post here.
As a disclaimer -- I am very aware that OR-Tools' Python code are just wrappers around their C++ source code. I'm just getting an odd discrepancy between a model ...
- 140
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2
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98
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TSP problem using Google's OR tools
This is the Travelling Salesperson Problem code from Google's OR tools. I used a simple instance that is defined in the data dictionary and has optimal value (sum of Euclidean distances) of 36.26 for ...
- 143
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81
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how the number of employees affects the married employee scheduling problem
My scheduling problem has a specific pattern of 2 days of work followed by 2 days off. Additionally, there is a week off after every 4 weeks of work. The scheduling matrix (P) has five different ...
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95
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Routing problem - How can I make use of the Clarke and Wright algorithm for a CVRP, when using the ortools library?
TL;DR: How can I specify to ortools to use only the Clarke and Wright algorithm.
Hello,
I'm trying to solve a CVRP. When exploring the my options, I stumble by the ortools library, it gets the job ...
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2
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116
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how to count the number of values that are greater than zero in OR-Tools
I am using OR-Tools for an employees scheduling problem. I have a dictionary that is defined as an IntVar, where such dictionary contains the number of hours that will be assigned to each employee, ...
- 31
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3
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104
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Constraint programming problem with matrix of integers
I am trying to solve the following problem. Suppose $A$ is an $m \times n$ matrix of integers with entries in $\{1, \dots, k\}$. There are two kinds of constraints on the entries of this matrix:
For ...
2
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1
answer
551
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What exactly does the AddHint() method in Google OR-Tools' CP-SAT solver do?
I have an optimization problem that I am solving with CP-SAT and I am using the Python interface. Moreover, I know a good feasible solution coming from a heuristic and I want the solver to start its ...
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[OR-Tools][CP-SAT] Implement an indicator function in a constraint
Good morning ! I would like to implement this constraint using CP-SAT (see image below).
x_i,j is a boolean variable, a and b are given. The problem is that I don't know how to implement the ...
1
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1
answer
346
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About circuit constraints in OR - tools
I am trying to implement a scheduling problem to solve with CP-SAT from OR-tools. There, in particular, for every machine I want to add a time transition constraint from every task that is performed ...
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123
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CP-SAT's `NumBooleans()` parameter
The solver API for CP-SAT offers the attribute NumBooleans, which is documented as "Returns the number of boolean variables managed by the SAT solver".
...
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101
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Alternative Approaches to Assignment Problem
I have a real world use case where I aim to optimize the assignment of trucks to orders of different sizes over a time window by minimizing some cost function (e.g. total distance traveled).
The below ...
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270
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Relevance of order of model construction in CP-SAT
Question 1: Is ortool's CP-SAT sensitive to the order in which a model is constructed?
In other words, does it matter which variables and constraints come first?
I am seeing a high performance ...
- 181
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70
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Multiplicity-Constraint in Constraint Programming Solvers
I need to solve a CSP with a constraint imposing upper bounds on the multiplicity of variables in a list.
More precisely, I need a constraint of the form
...
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429
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OR-Tools: Nonlinear constraints?
I have inherited a reasonably simple ortools-based optimizer (Python) with linear relationships that I need to non-linear-ize, and I have no idea how to do that.
The relevant part of my problem looks ...
- 119
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568
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TypeError: unsupported operand type(s) for *: 'IntVar' and 'float' in ortools [closed]
I am trying to implement a constraint as follows:
...
- 181
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655
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Google-OR tools vs Pyomo and other commercial Solvers for solving a simple maximum flow problem
I have implemented a Pyomo model for solving maximum flow problem as a subroutine of an algorithm. However, the approach does not scale very well because Pyomo does not provide a very good way to re-...
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106
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Control load per trip in multi trip VRP in ORTools
I have implemented multitrip VRP in ortools (To be specific, solved CVRPTW with virtual depots). Maximum number of trips per vehicle is limited to 2. I want to put a hard constraint that load carried ...
- 181
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1
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174
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Applying weights to assignment problems for linear MIP solvers
In previous posts, A & B, I posed the Movie Theater Problem. In short, the movie theater problem encompasses assigning viewers to seats such that the distance between viewers is maximized, however,...
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158
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Google OR Tools: Iterative Assignment Problem
This question is a Google OR-Tools specific implementation of recommendation from a previous question.
In short, the movie theater problem encompasses assigning viewers to seats such that the distance ...
- 481
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2
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127
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Mixed Integer Programming: Iterative assignment problem
I have a real world problem, which is analogous to the below toy problem, which I call 'The Movie Theater Problem' (TMTP.)
In TMTP, movie viewers are assigned seats which principally balances two ...
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193
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Or-tools : CVRP multiple time window with multiple location
I am using or-tools to solve a CVRP with multiple time window, and multiple location.
Meaning that a customer can move during the day.
I can't achieve to add constraint like if i deliver the customer ...
- 31
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1
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114
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Simple Constraint Programming Problem: docplex works but equivalent ortools model is infeasible
I have a simple constraint programming model which can be solved using the docplex library, however I am struggling to implement the same model using ...
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451
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Maximize the minimal distance between true variables in a list
I'm using the OR-Tools CP-SAT solver on a list of $n$ boolean variables $x_i$. I'm trying to maximize the minimal distance between two true variables in this list, as illustrated by the following ...
- 235
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111
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(OR-Tools) Custom Function to Evaluate Intermediate Solutons
I have a system with $k$ tasks, where each task is a state in a Markov chain. I am working on allocating agents to each task. I would like to achieve a specific distribution of the agents among these ...
- 325
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80
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Circuit constraint leading to infeasibility if there are 0 jobs producable one a machine
Using the CP-SAT Solver:
My Model turns infeasible whenever there is no job available for a machine. Not every job can be built on every machine. Example Situtations:
Less jobs than machines
No jobs ...
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votes
1
answer
401
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Google OR-Tools, algorithms under the hood?
Under the hood, what algorithms does Google OR-tools support?
From adjacent questions, I saw someone as this question and the answer linked to this repo. However, these sources just show how to use ...
- 481
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249
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Multiple Knapsack with Varying Values
I wish to assign customers to their nearest distribution hubs. These hubs have maximum capacities however, and if these are breached I would like to assign customers to the next most appropriate hub.
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1
answer
191
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RAM overflow when scheduling 1000+ intervals
Due to the answers to this and this questions, I was able to find the optimal solution for scheduling problem. However, if there are many tasks that must be scheduled, e.g. 1000+, then the solver ...
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1
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320
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CP-SAT solver doesn't use all space available for scheduling
This problem is a continuation of this problem. The issue here is the solver doesn't use the whole space available for the scheduling and thus some jobs are not being scheduled. For example: we need ...
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247
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Force gaps between tasks, tasks are scheduled within their job's time windows in Jobshop problem
The problem I'm trying to solve is a modification of the original Jobshop problem. The additional constraints are:
There is only one machine for all jobs and their tasks.
Each job has a priority (...
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1
answer
301
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Minimum cost flow problem with multiple arcs between nodes in Python / Google OR
Is it possible to work with multiple arcs between 2 nodes within Google OR?
Or are there better modeling techniques?
I want to optimize flow from supply to demand areas, where supply and demand are ...
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166
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Can Pyomo be linked with Google's GLOP or CP-SAT solvers?
Pyomo can be linked with several solvers Open source and commercial ones.
I was wondering if Pyomo can be linked with Google's GLOP or CP-SAT solvers?
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Scheduling optimization, Adding 4 day same shift and 3 day off weekly constraint
Am writing a small scheduling program in C# for a group of 7 staff who will be working in three shifts daily for 4 weeks. Am using the google OR-Tools Template, but i have modified it abit
This is the ...
- 121
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145
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Modeling Multi-Agent Collision in Google CP-SAT Solver
I would like to implement a solution for Multi-Agent Pathfinding Problem using Google's CP-SAT Solver.
How do I implement the constraint that prohibits 2 or more agents from occupying the same cell at ...
- 325
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2
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227
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Google CP-SAT Infeasible ILP for Large Problem Area
I am trying to generate a shortest path between source and sink in a square grid of cells. I am using the Google CP-SAT solver ...
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1
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370
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How to Model Path Being Only Through Adjacent Cells
I am trying to develop a MILP for a path planning problem. I am operating on a grid of cells that represents a map. The arrangement of cells in the grid represents the placement of the cells in real ...
- 325
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199
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or-tools: job shop problem never exists not finding additional solutions
I am trying to solve a flexible job shop problem variant using or-tools.
And in some input configuration, in general after one month of scheduling time, I am facing a weird behavior.
I am aware that ...
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451
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Incorporating OR-Tools in a CMake Project
I'm trying to incorporate or-tools into my cmake project.
I've tried some of the suggestions given by the project maintainers, who give a few different ways to integrate or-tools in the readme and in ...
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710
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How does OR-Tools improve on an initial solution to CVRP?
I have an initial solution to a CVRP instance which I am setting as input to the solver. The solver as expected returns an improved solution. I have a few questions regarding the solver.
How does the ...
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420
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Circuit constraints in ortools
I am looking to assign tasks to people. Each successive task should be started after the first one is finished and should be started at the same location as the preceding task. While the time ...
