13 votes
Accepted

How to implement a custom global constraint in IBM's ILOG CP optimizer

The Graph Coloring example shipped with CP optimizer (file: color.cpp in the examples directory): ...
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9 votes

Constraint programming using solver: how to state the time limit of search?

What Nikaza said, and also: problems of this kind often have a large number of solutions that differ only by trivial permutations/relabellings/reorderings. For example, if one worker is assigned 10 ...
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6 votes

Constraint programming using solver: how to state the time limit of search?

CPLEX is probably spending 15 hours trying to reduce the optimality gap. This is very common issue in MILP problems. The way MILPs are solved is commonly to make all integers continuous and solve the ...
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4 votes
Accepted

CPLEX CP Optimizer Java API function missing

I think that you're looking for function IloCP::typeOfPrev. Its documentation is for example here, the description of the general concept is here. Basically, each ...
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4 votes

Optimal Energy Charging/discharging Scheduling Problem

I assume that you want to model your problem in OPL. Here is a sketch of the model. ...
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4 votes

Can I export to .cpo file using OPL?

Other options: Run your model from the command line using oplrun. Using option -d you can specify to dump your model into a <...
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4 votes
Accepted

Can I export to .cpo file using OPL?

The steps taken from the IBM Knowledge Center are: Create a new settings file Change the export format to CPO Add the settings file to the default run configuration Run the run ...
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  • 5,756
3 votes

Constraint programming using solver: how to state the time limit of search?

CP Optimizer is doing a search for progressively better solutions. Each time it finds a feasible solution, it restricts the remainder of the search to solutions with better objective values than what ...
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  • 31.1k
3 votes

CPLEX CP Optimizer Java API function missing

I'm not a CP Optimizer user, so this may be clunkier than necessary (by an order of magnitude). I'm going to assume that your setup times satisfy the triangle inequality (meaning it's faster to go ...
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  • 31.1k
3 votes

Could DOcplex.CP recognize that it solves the graph coloring minimization problem?

The automatic search of CP Optimizer does not try to recognize a graph colouring problem. As you notice, fixing the colour of one variable to get rid of some symmetries in the model may help. ...
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2 votes

ILOG CPOptimizer soft constraints (multiple solves reusing searched space)

I am fairly certain that you cannot resume solution from the previous final state after altering the model. This is a known fact with CPLEX, presumably the same with CPOptimizer for essentially the ...
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  • 31.1k
2 votes

Could DOcplex.CP recognize that it solves the graph coloring minimization problem?

within 4s with your data set CPLEX both MIP and Constraint Programming prove optimality In OPL ...
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2 votes

Scheduling with transition costs - DOCPLEX

According to you mentioned, it sounds like the Resource‐Constrained Project Scheduling Problem (RCPS). To execute such a problem with CPLEX, you have two different options. First, develop a mixed-...
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  • 6,114
1 vote

How to implement a custom global constraint in IBM's ILOG CP optimizer

The answer provided by Joris Kinable is correct for CP Optimizer versions up to 12.7.1 Starting from 12.8.0 they made changes in the API (more info here). What this basically means is that you should ...
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