Questions tagged [or-tools]
Questions related to or-tools, Google's open-source software suite for optimization
117
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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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2
answers
80
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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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3
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1
answer
174
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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 ...
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1
vote
1
answer
57
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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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2
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1
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160
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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 ...
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1
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381
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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:
...
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0
answers
327
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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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2
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1
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66
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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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136
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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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1
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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 ...
- 471
2
votes
2
answers
103
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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 ...
- 471
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0
answers
122
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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 ...
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vote
1
answer
75
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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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3
answers
420
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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 ...
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1
vote
1
answer
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
2
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1
answer
74
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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 ...
- 35
3
votes
1
answer
282
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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 ...
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1
answer
230
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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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2
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1
answer
170
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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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2
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1
answer
203
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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 ...
- 75
3
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1
answer
202
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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
217
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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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answers
121
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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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142
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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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vote
1
answer
116
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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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vote
2
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198
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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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6
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1
answer
361
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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 ...
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1
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168
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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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0
answers
311
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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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5
votes
1
answer
513
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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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0
answers
355
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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 ...
2
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1
answer
256
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Mathematical Formulations for Google-OR tools
I recently started looking into Google-OR tools. However, I do not see mathematical formulations of any of the problems the OR-tools can solve. Without looking at the model (set, objective, ...
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1
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149
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OR-Tools Cost Function Integration
I am modeling a problem similar to the job shop problem (tasks with start times, duration, and predecessors) and my objective is to minimize the makespan, with Python and OR-Tools.
start[i] is an ...
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3
votes
2
answers
705
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Simple example of finding Hamiltonian path using Google OR-Tools?
I'd like to test how good/fast OR-Tools is in finding hamiltonian paths on some (big) directed graphs.
But I can't find simple enough (for me) examples.
Something like these ones (or even simpler), ...
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3
votes
1
answer
140
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"Complex" scheduling problem model structure
So, I'm modelling a job assigning problem in OR-Tools CP-SAT. I want to maximize rescheduled jobs based on some constraints. Right now jobs in my model look like this:
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2
votes
2
answers
362
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Modeling Refueling in Vehicle Routing Problem in OR-Tools
As the title suggests, I am working on a problem that pertains to single-vehicle routing, where certain vertices in V are not mandatory to be visited, but are ...
- 325
4
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1
answer
391
views
Can I print the linear programming sensitivity analysis report using google or-tools?
One can solve the linear programs using google or-tools with GLOP solver. I wonder if there is a way to print the sensitivity report (like shadow prices etc.).
1
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1
answer
231
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How to stop the vehicle from reaching the depot in between the trip
Requirement overview:
The trip route can have the following type of task
Delivery only
Pickup only
Pickup from one location and deliver to another location
Condition: Once a trip starts from depot, ...
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2
votes
1
answer
337
views
Minimize capacity of vehicles in VRP with OR Tools
I'm using Google's OR tools in Python to do some optimization in routing in a model where I need to pick just the bare minimum to satisfy a demand.
The situation is, let's say I need 100 units of the ...
1
vote
1
answer
438
views
Custom lazy callback constraints using Google OR-Tools linear solver?
Is it possible to implement custom lazy callback constraints using OR-Tool's base linear solver?
Through Google's docs, I've seen their TSP examples using the constraint solver ...
- 138
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vote
1
answer
224
views
Circuit constraint respecting the order of the next n jobs / jobs on each machine starting at 0
I am working on a scheduling problem in OR-Tools using the CP-SAT solver.
I'm working with
python but I managed to rebuild this solution as starting point:
Optimal way to ensure optional intervals are ...
- 35
1
vote
0
answers
77
views
Minimizing total number of banners used in the cover buildings problem modelled
I was watching a video about Google OR-Tools where they were solving this cover building problem from Codility challenges using constraint programming.
In short, you have a list of building heights, e....
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0
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0
answers
303
views
OR-Tools addElement constraint
I am just not able to grasp how can I use the addElement constraint of OR-Tools. I am trying to model the following constraint written in MiniZinc:
...
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4
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1
answer
385
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Is Google's OR-tools for professional work? Specially VRP module [closed]
So I've been given at work a project which consist on finding optimal pathing for trucks in certain custom scenarios. When I discovered this tool I thought it worked wonders for what I understood the ...
6
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1
answer
621
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Python "Coffee Shop Scheduling Problem" - Scheduling Lunches/Breaks
I'm working on an employee scheduling program in python. Having never done this before, I've been researching different libraries that can be used to accomplish the task.
Unfortunately, none of the ...
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2
votes
1
answer
496
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Using OR-Tools with .NET and GUROBI
We want to model our MILP problem with Google OR-Tools in .NET, and solve it using GUROBI (solver may change in the next 1-2 years). However, we couldn't find the correct syntax to call GUROBI.
https:/...
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1
answer
181
views
Scheduling when task duration longer than working interval
I'm trying to modify the job shop example for CP-SAT solver. (https://developers.google.com/optimization/scheduling/job_shop)
I'm limited to 8 hours working day,
So I defined a list of NewIntervalVar()...
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2
votes
1
answer
481
views
Set value based on if other variable is in specific range
I have the following problem.
number_of_machines is controlled by other constraints. I need to set line variable to specific value based on "range" ...
- 65
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0
answers
243
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Set Covering and Column Generation
I need some set covering and column generation examples in OR-Tools python.
If anyone can provide or direct me to some resources that would be great..!
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2
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1
answer
191
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A specific case of a resource constrained project scheduling problem with partially renewable resources (RCPSP/$\pi$) - OR-Tools
I've been trying solve a specific case of the resource constrained project scheduling problem with partially renewable resources (RCPSP/$\pi$ in the literature e.g. this paper). These resources are ...
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