Questions tagged [or-tools]

Questions related to or-tools, Google's open-source software suite for optimization

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2
votes
1answer
47 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" ...
0
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0answers
111 views

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..!
3
votes
1answer
90 views

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 ...
1
vote
1answer
52 views

Print Intermediate Solutions of Scheduling Problem and tackling FLAGS in jupyter notebook

I tried this code and it goes on and I'm clueless when it'll end so I manually interrupt it. Is there any way we can see intermediate solutions that are feasible solutions and can we limit time or ...
2
votes
0answers
99 views

Multiple Depot/Crew Office Bus Driver Scheduling Modelling

I'm working on Bus Driver Schedule with multiple add-on constraints that are complex and hence trying to figure out how this can be achieved. Reference of Bus Driver Scheduling using OR-Tools:- https:/...
2
votes
1answer
71 views

Extracting CNF representation of my problem from SAT solver

As I know, any SAT solver such as or-tools or cplex cp optimizer converts a given problem to CNF form in the first place. Is it possible to extract the resulting CNF representation from or-tools or ...
2
votes
1answer
123 views

OR-Tools, How to avoid dividing by zero

Problem: There is an order to fabricate some products of total number, let's say 200 (all products are the same). We have some number of factories, let's say 5. Every factory has different number of ...
4
votes
1answer
181 views

Using VRPy and OR-tools in Python to solve the DCVRP

This question is a follow-up to this one. Since I understand the complexity of the problem I have been underestimating, I turned my attention to off-the-shelf solvers, like VRPy and OR-tools. I would ...
2
votes
2answers
107 views

OR-Tools: Partial Solution ignored due to "unknown rate is too large"

With SetHint() from the OR-tools linear solver I am trying to pass a feasible solution to my problem. But I receive the following warning: ...
1
vote
1answer
149 views

Travelling salesman problem variant without returning to the starting point

I tried the code provided on the link : https://developers.google.com/optimization/routing/tsp The actual requirement is to traverse all paths without returning to the start point with minimum ...
4
votes
2answers
458 views

find suboptimal solution, if no optimal solution exists?

I am using or-tools linear solver. and my problem ends up having no optimal solution. how can I tell the solver to find a suboptimal solution?
1
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0answers
55 views

Modified bus scheduling problem question in ortools

Has been crossposted in stackoverflow. I want to solve the bus scheduling problem using ortools with some minor modifications. In my case, the max number of drivers is known. The modifications I would ...
0
votes
0answers
89 views

Mixed Integer Programming - Model Formulation for A Resource Allocation Problem

There are a number of orders, which needs to be shipped. For each order, there may be 1 to 3 route options. The problem here is to find out the best allocation (combination) of orders among these ...
2
votes
0answers
43 views

Add Variables in Bulk for ortools

I am using the Python ortools to solve large LPs where the number of variables and constraints are in the hundred thousands ($10^5$). Surprisingly, it takes longer ...
1
vote
1answer
69 views

CP-SAT _ Summing variables under conditions

I have been working lately on scheduling optimization using CP-SAT in OR-TOOLS and now I'm at the point where I need to start considering due dates in my model. I didn't want to put them as ...
1
vote
1answer
94 views

Problem with setting up gurobi with OR-tools

I am trying to setup Gurobi with Google OR-Tools with the function pywraplp.Solver.CreateSolver("GUROBI"). The function returns None, which could occur if ...
2
votes
0answers
178 views

modify pickup and delivery problem to only delivery scenario in google OR-tools

I am using Google OR Tools for solving the capacitated vehicle routing problem.I want to implement optimization solution for delivery problem.For example there is one storage location which load all ...
2
votes
2answers
303 views

Cutting Stock Problem : Mixed Integer Programming

I am asked to solve the following problem: The problem: You were asked to repair a farm house with sheets of plywood. You were given thirty sheets of plywood. (each size = 10ft x 10ft) The house ...
3
votes
2answers
144 views

Google OR returning different values depending on language

Lately, I have been working on a CP-SAT model for solving multi-resource flexible job shop problems. I used the code (1) as an inspiration for building code (2) in Python which works well. Then I had ...
7
votes
0answers
347 views

OR-TOOLS : delivery node with multiple possible pickup nodes

I am using ortools to model a VRP with pickup and delivery constraints, where pickups can be done at different nodes. For example, if node A has a demand, it must be picked at node B or C. Here is how ...
3
votes
0answers
104 views

Production planning for a video game economy

I'm a software developer who likes to play a video game that has a complex economy. I realized that the type of problem I'm trying to solve mimics real life operations research problems, and I am ...
6
votes
1answer
211 views

OR-TOOLS : is it possible to partially fulfill a demand?

I am working on a vehicle routing problem with or-tools. Is it possible to partially fulfill a demand? I know it is possible to drop nodes with the disjunction constraints. But in this case, a node is ...
2
votes
1answer
466 views

How to know which constraint in CP-SAT did not meet the feasibility gap

Is there any systematic way to retrieve some information on the constraint that caused infeasibility in Or.Tools CP-SAT? ...
2
votes
1answer
96 views

How to model a set of integer variables getting assigned different values than another set of integer variables

Assume we have variables $x_1, x_2, x_3, x_4$ that each can belong to $\{1,2,...,10\}$. How can we model a constraint that variables $x_1, x_2$ get assigned different values than $x_3, x_4$? Because ...
2
votes
3answers
286 views

How to model two variables to NOT to belong to the same set partition using Constraint Programming

Assume we have two variables $x,y \in S$ where $S=\{1,2, \dots, 1000\}$. Also, we are given a partition of set $S$ as: $S_1 = \{1,2, \dots, 249\}$ $,S_2 = \{250, \dots, 499\}$ $,S_3 = \{500, \dots, ...
3
votes
0answers
83 views

Best known results on the flexible jobshop benchmarks

Is there a website that compiles the best known results on the flexible jobshop problem ? I know there was a blog post/article by Quintiq, a (deleted) blog post on CP Optimizer, some more recent ...
1
vote
1answer
129 views

Flexible Job Shop Problem with several resources per alternative - Ortools

It has been quite a journey for me to go from 0 to understanding the job shop (js) and the flexible job shop (fjs) examples given by Google's ORTOOLS team. Now the time has come for me to start ...
3
votes
0answers
45 views

High-mix manufacturing capacity

I'm not an expert in OR but I would like to determine what is the maximum manufacturing capacity of a plant (or how much a plant can produce of mix products). Each person in the plant has a known set ...
4
votes
1answer
111 views

maximum number of BoolVar 's before or-tools is no longer feasible to use

The standard nurse scheduling problem which is used as an example for OR-Tools (see for example https://developers.google.com/optimization/scheduling/employee_scheduling) attempts to assign boolean ...
4
votes
1answer
224 views

Best way to solve an allocation problem

I have the following problem: I have products with different attributes (price, weight, category) and I have a list of clients. Every client has an "affinity value" with every product, the ...
1
vote
1answer
134 views

How to balance the workload of teachers in OR-Tools (maximization of the minimum)

I am very new to optimization and OR-Tools. I am trying to solve a very simple question. Let's assume that we have $n$ students. Each student needs to be assigned to only one teacher as a supervisor. ...
4
votes
1answer
161 views

Is it possible to solve VRP using OR-Tools CpModel, instead of RoutingModel?

Is it possible to solve VRP using OR-Tools CpModel, instead of RoutingModel? I want to do synchronized VRP, which is combining vehicle routing and scheduling constraints
5
votes
2answers
247 views

Priority List Constraint

I used the Vehicle Routing Problem example that has the objective of minimizing total distance traveled for each vehicle. Suppose that each order to pick up for each vehicle at each node has a ...
3
votes
2answers
640 views

How to add logical OR constraint in OR-Tools?

Let's say nurses normally do 1 shift for d in all_days: for s in all_shifts: model.Add(sum(shifts[(n, d, s)] for n in all_nurses) == 1) But I want to ...
1
vote
0answers
71 views

Fixed cost associated to SlackVar(waiting time cost) [CVRPTW]

I'm modeling a CVRPTW with some features: Each type of vehicle has a cost per km and a fixed cost per trip. To calculate these costs, I am using these methods for this: ...
4
votes
1answer
177 views

Adding a hard and soft upper bound constraint of number of locations to visit (VRP)

I went through the Vehicle Routing Problem example and was able to replicate it. On the example, there is a constraint added for vehicle maximum distance as shown below: ...
4
votes
2answers
620 views

CP-SAT over CBC for MIP, is it worthwhile?

I am working in an integer optimization problem. All of the decision variables are binary, and the objective is to minimize some cost function. I currently am implementing CBC, but I have been reading ...
4
votes
1answer
309 views

Solving vehicle routing problem in java

I am trying to solve vehicle routing problem in java and I am looking for libraries for the same. I did a POC using google or-tools and it seems to be solving all my use cases. I would like to know if ...
7
votes
1answer
639 views

CP-SAT ortools - Is there any complete list of possible/available StringParameters for the CpSolver?

I wonder if there is any list of string parameters documented. So far, I only know max_time_in_seconds and num_search_workers. ...
3
votes
1answer
133 views

Optimal way to ensure optional intervals are consecutive in OR-Tools

I am trying to solve a scheduling problem in OR-Tools. There are lots of "events" that need to be scheduled to "blocks" (essentially half-days). I am naturally using optional intervals for the events. ...
6
votes
1answer
538 views

Solution time out for VRPTW in or-tools

I am experimenting around with or-tools and somehow I can't get a solution for the VRPTW problem for any of the instances I have tested from Gehring & Homberger ...
5
votes
2answers
382 views

How to measure model quality in OR-Tools?

After creating my model for a problem, what steps should I take to test if a change in the model is actually helpful or not? In Python, ...
4
votes
1answer
243 views

How exactly does OptionalIntervalVar work in OR-Tools?

I created OptionalIntervals for a number of tasks: ...
4
votes
1answer
285 views

TSP with constraints in OR Tools

I am completely new to OR Tools, but what I have tried so far seems very powerful. I have, however, run into a problem that I cannot seem to figure out how to solve. I am trying to model a TSP ...
5
votes
1answer
629 views

assigning values to IntVar if and only if BoolVar, else zero [or-tools]

If I have an IntVar s[j] stored in a vector s, is it possible to iterate for (a period of ...
6
votes
0answers
120 views

OptionalIntervalVar enforced but not working OR-TOOLS

I'm using OptionalIntervalVar and then maximizing the starts. The optimal solution is not affecting the other variables that creates the ...
6
votes
0answers
121 views

Modelling issue with precedence constraint in OR-Tools

I'm trying to solve an RCPSPDc model It is infeasible, although Ilog Cplex solves it, so I think I have a modelling issue. I have more constraints but the precedence is the one that makes it ...
3
votes
1answer
144 views

ValidateModel or tools in c++ and proto problems

I'm trying to validate my model, this is the relevant part of my code: ...
5
votes
0answers
85 views

Modelling issue with rcpsp and boolean expressions

I'm trying to solve an RCPSPDc problem in OR-Tools with CP-SAT solver. In my RCPSPDc model (with discount rate) i want to set this objective: $$\max_{s}\sum_{j\in J}\text{profit}_{j}\cdot \frac{1}{(1+...
5
votes
1answer
805 views

Cumulative Constraint OR-Tools

I'm trying to solve an rcpsp model. I can't find documentation for the AddCumulative function of OR-Tools. How should this function be used? I want to write this ...