Questions tagged [or-tools]
Questions related to or-tools, Google's open-source software suite for optimization
122
questions
6
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0
answers
198
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
0
answers
151
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
1
answer
183
views
ValidateModel or tools in c++ and proto problems
I'm trying to validate my model, this is the relevant part of my code:
...
4
votes
0
answers
100
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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:
$$\max_{s}\sum_{j\in J}\text{profit}_{j}\cdot \frac{1}{(1+...
5
votes
1
answer
2k
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Cumulative Constraint OR-Tools
I'm trying to solve an rcpsp model.
I can't find documentation for the AddCumulative function of OR-Tools. How should this function be used?
I want to write this ...
8
votes
1
answer
409
views
Precedence Constraint in OR-Tools
I'm trying to write this constraint in C++ and add it to my model (addLessOrEqual):
$$\text{start}_{i}+\text{duration}_{i}\le\text{start}_{j}$$ for an $(i,j)$ arc ...
3
votes
0
answers
175
views
Power of variable or tools
I'm working with OR Tools in Python and I need to define the objective function an expression of the variables. In particular, the objective function is
$$\frac{c_j}{1.7^{s_j}}$$
with $c_j$ ...
- 131
10
votes
1
answer
1k
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Floating points in ORtools
I'm trying to solve an RCPSPDc model (maximizing the net present value instead of a makespan). The objective function is: $\sum\limits_{j \in \text{Tasks}} e^{-\theta\cdot s_{j}}\cdot p_{j}$, where $...
8
votes
1
answer
739
views
Travelling salesman problem with given number of locations to visit
There's a great example here of how to find a solution to the travelling salesman problem:
...
- 271
6
votes
1
answer
971
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Constraint Programming OR-Tools finding Matrix Combinations
As a similar post of mine Find all Combinations of a Matrix I am trying to find matrix combinations with entries $>0$ meaning for a matrix
\begin{bmatrix}
0 & 1 & 3 \\
5 & 2 & 1 \\
...
- 1,193
9
votes
1
answer
569
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TSP problem: traveller does not visit all nodes - Google OR-tools
Context:
I am dealing with a kind of scheduling problem, in which I have a set of tasks and machines. All tasks must be assigned to machines (not necessary all of them). In addition to that, I must ...
- 1,133
11
votes
1
answer
2k
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Incorrect solution for Vehicle Routing Problem in or-tools
I am trying to understand how the Vehicle Routing Problem is solved in OR-Tools.
Using the example given here, I have tried to solve the following distance matrix with 9 separate vehicles:
...
- 211
7
votes
1
answer
369
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Shipments consolidation - how to model mutually exclusive items with OR-Tools CP Solver in Python (multi-knapsack, updated)
I am implementing a solution for packages consolidation (basing on Nurse Problem solution) with OR-Tools CP Solver.
There is a factory that manufactures some small Packages that need to be ...
- 73
8
votes
3
answers
1k
views
Maximize assigned tasks to each worker
In a scheduling problem I want to assign the maximum number of tasks to one worker before assigning it to another. For example, if I have $10$ tasks and $2$ workers, the best assignment would be $(10, ...
- 1,384
4
votes
1
answer
409
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Machine Allocation & optimal Utilization using python
Problem statement: Meet the demand which can be met across 2 facilities each having multiple machines where several components are made. The objective is to find the optimal solution to meet the ...
- 141
7
votes
2
answers
576
views
CP Framework/Solver for .Net Core
First I want to say that I'm very new to this field.
As far as I understand it, there are two different ways to use a Constraint Programming (CP) Solver:
Using the API from the Solver itself. For ...
- 343
24
votes
3
answers
9k
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What is the purpose of libraries like Pyomo and Google OR tools?
I'm new to the OR world, and trying to learn the various tools available. I originally thought that Pyomo and Google OR tools were open source alternatives to commercial solvers like Gurobi or CPLEX.
...
- 2,069
11
votes
1
answer
688
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How to solve the Cumulative Traveling Salesman Problem using or-tools in python?
The objective of the Cumulative Traveling Salesman Problem (CTSP) is to minimize the sum of arrival times at customers, instead of the total travelling time. This is different than minimizing the ...
8
votes
1
answer
188
views
Strategy for filling a table only slightly dependant on the number of columns
I'm using the OR-Tools CP-SAT solver to fill a table with integers, with various constraints, as illustrated by the x in the following figure.
...
- 235
11
votes
1
answer
450
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Modeling an assignment/scheduling problem to minimize total wait
I have an assignment type problem in which there is a set of students, $S$, and a set of training classes $T$. Each training has a fixed start and end day and can accommodate at most 1 student. In ...
- 111
9
votes
3
answers
3k
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Google - OR tools for workforce scheduling problems
Has anyone used the google OR tools in python to solve the workforce scheduling problem. Can you please let me know
Advantages and Disadvantages
Any issues faced during usage and implementation
16
votes
1
answer
1k
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Warm start CPLEX using google or-tools
I have been trying to use the SetHint python API in google or-tools to warm start MIPs and solve it using CPLEX. It looks like my hints are accepted by the SetHint function but I am not sure whether ...
