All Questions
40
questions
11
votes
1
answer
761
views
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 ...
10
votes
1
answer
2k
views
Floating points in OR-Tools
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 $...
9
votes
3
answers
2k
views
Open source MILP solver for quick “good enough” solution
I have a problem that I have already posted elsewhere in OR.stack, but the question is focused around a large binary MILP (about 1 million decision variables). Ultimately, I am more time constrained ...
- 335
9
votes
1
answer
624
views
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
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, ...
- 1,414
8
votes
1
answer
760
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
367
views
Interface for Cbc - COIN-OR
I would like to code some IP/MIP models in python and test them with an open-source solver. As of now, I only know the Cbc - COIN-OR open-source solver.
I have already tried the or-tools interface, ...
- 1,193
6
votes
2
answers
705
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 ...
- 101
6
votes
1
answer
1k
views
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
6
votes
1
answer
923
views
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 ...
- 63
4
votes
2
answers
613
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:
...
- 93
4
votes
1
answer
651
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:
...
- 101
4
votes
1
answer
643
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 ...
- 41
4
votes
1
answer
467
views
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
3
votes
2
answers
3k
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 ...
- 131