Questions tagged [job-shop-scheduling]

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Use of variance in job ordering

For a job-shop-like problem I have some constraints of this form: $$ c_i \geq s_i + d_{iom} z_{iom} $$ $z_{iom}$ is a binary enabler, $d_{iom}$ is the delay on job $i$ for operation $o$ done by ...
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  • 585
-1 votes
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Assignment Problem with continuous decision variable

I have to solve a problem from industry where there are a number of machines which should be assigned to a number of tasks. The difference from the general assignment problem is tough, that the ...
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4 votes
2 answers
171 views

Identifying problem: Assignment + Job Shop Scheduling

I am new to OR. Hence, I want your advice on the problem I am trying to solve: Given: $O_1 \rightarrow O_2 \rightarrow O_3 \rightarrow ... \rightarrow O_n$: the sequence of operations to produce $1$ ...
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0 votes
1 answer
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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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MIP gives out zero as best solution when trying to optimize MIP model for flexible job-hop

I have implemented an existing MIP Model into python with the python-mip solver and somehow I only get '0' as a solution to my minimization problem. What could be the problem? I am fairly new to LP ...
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2 votes
1 answer
103 views

opposite of no_overlap constraint in docplex for CP

I am using python for CP solving. I would like to know if there is constraint that does the opposite of no_overlap. This will be like overlap(interval, arr, n) interval - single interval variable arr -...
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4 votes
2 answers
259 views

Python Pulp - LpMinimize Not Returning Expected Output - Scheduling Problem

I'm working on my first pulp model and something isn't going quite right. It looks like it's close, but for some reason it is not respecting one of my constraints... It's a scheduling problem and I am ...
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3 votes
1 answer
133 views

Model generation for large-sized instances

I have a scheduling model where each job $p$ requires three operations (with fixed precedence and they must happen in a row) for a fixed number of $i$ service sessions (each session on a specific day)....
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  • 293
1 vote
1 answer
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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 ...
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3 votes
1 answer
56 views

What are the alternatives to front loading of jobs/tasks/projects?

When assigning jobs (or tasks or projects) to a starting time, with a ready and due time for each job, there are different scenarios: A) Front loading: Assign all jobs as soon as possible. As close ...
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