multiple solutions in MIP CBC

[Alessandro Zanarini]

Hi all -

I have a pure feasibility problem that I have implemented with a simple CP model (python). I need to list all the feasible solutions.

For the sake of comparison, I would like to create a MIP model that does the same (CBC). How can I retrieve multiple solution from the solver?

Thanks

Alessandro 

[Driss Lahlou]

Hello Alessandro,

As for your first question, you can use MakeAllSolutionCollector(), it will return a SolutionCollector that has the method Solution, you can use it to get the nth found solution.

I hope this helps.

Regards,

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driss

[Driss Lahlou]

Addendum :

Returning multiple solutions from solvers like CBC is not supported. You can retrieve only the best solution.

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[Alessandro Zanarini]

Hi,

thanks for the reply. I was actually referring to the enumeration of the MIP solutions.

For reference, I ended up adding a cut after each solution has been found, and solve again (though it might not be the most efficient way to do it...)

Best,

Alessandro

[Laurent Perron]

I do not know of any other portable way.

I know cplex supports enumerating solutions (and maybe other solvers do), but we do not support it. 

Thanks

Le mar. 22 nov. 2016 à 07:13, Alessandro Zanarini <alessandr...@gmail.com> a écrit :

Hi,

thanks for the reply. I was actually referring to the enumeration of the MIP solutions.

For reference, I ended up adding a cut after each solution has been found, and solve again (though it might not be the most efficient way to do it...)

Best,

Alessandro

On Mon, Nov 21, 2016 at 2:51 PM, 'Driss Lahlou' via or-tools-discuss <or-tools...@googlegroups.com> wrote:

Addendum :

Returning multiple solutions from solvers like CBC is not supported. You can retrieve only the best solution.

On Mon, Nov 21, 2016 at 2:14 PM, Driss Lahlou <dla...@google.com> wrote:

Hello Alessandro,

As for your first question, you can use MakeAllSolutionCollector(), it will return a SolutionCollector that has the method Solution, you can use it to get the nth found solution.

I hope this helps.

Regards,

On Sat, Nov 19, 2016 at 4:19 PM, Alessandro Zanarini <alessandr...@gmail.com> wrote:

Hi all -

I have a pure feasibility problem that I have implemented with a simple CP model (python). I need to list all the feasible solutions.

For the sake of comparison, I would like to create a MIP model that does the same (CBC). How can I retrieve multiple solution from the solver?

Thanks

Alessandro 

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driss

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[Alessandro Zanarini]

Hi Laurent,

thanks for the feedback.

Ciao,

Alessandro

On Tue, Nov 22, 2016 at 10:34 AM, Laurent Perron <laurent...@gmail.com> wrote:

I do not know of any other portable way.

I know cplex supports enumerating solutions (and maybe other solvers do), but we do not support it. 

Thanks

Le mar. 22 nov. 2016 à 07:13, Alessandro Zanarini <alessandr...@gmail.com> a écrit :

Hi,

thanks for the reply. I was actually referring to the enumeration of the MIP solutions.

For reference, I ended up adding a cut after each solution has been found, and solve again (though it might not be the most efficient way to do it...)

Best,

Alessandro

On Mon, Nov 21, 2016 at 2:51 PM, 'Driss Lahlou' via or-tools-discuss <or-tools-discuss@googlegroups.com> wrote:

Addendum :

Returning multiple solutions from solvers like CBC is not supported. You can retrieve only the best solution.

On Mon, Nov 21, 2016 at 2:14 PM, Driss Lahlou <dla...@google.com> wrote:

Hello Alessandro,

As for your first question, you can use MakeAllSolutionCollector(), it will return a SolutionCollector that has the method Solution, you can use it to get the nth found solution.

I hope this helps.

Regards,

On Sat, Nov 19, 2016 at 4:19 PM, Alessandro Zanarini <alessandr...@gmail.com> wrote:

Hi all -

I have a pure feasibility problem that I have implemented with a simple CP model (python). I need to list all the feasible solutions.

For the sake of comparison, I would like to create a MIP model that does the same (CBC). How can I retrieve multiple solution from the solver?

Thanks

Alessandro 

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driss

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