[SCIP] branch-and-price-and-cut

[Gerald Gamrath]

Hi Marko,

about 2): did you set the constraints to initial?

Best,

Gerald

On 6/20/22 08:18, Horváth Markó wrote:
> Dear all,
>
> none of my attempts were succesful. I have two further questions.
>
> 1) Is it possible to add new rows to the problem of the new child 
> nodes during a branching? When using scip_execlp, I could add (stick) 
> new constraints to the child nodes, but I cannot find similar 
> functionality for new rows.
>
> 2) Assume I added new constraints to the child nodes during branching. 
> When a node is focused, is it possible to add new rows to the problem 
> (based on these constraints) before the first LP is solved? I tried to 
> modify the LP inside callback scip_active, however, nothing happened.
>
> Best regards,
> Marko
>
> 2022. 06. 13. 9:42 keltezéssel, Horváth Markó írta:
>> Dear all,
>>
>> I'm working on a branch-and-price-and-cut approach. Actually, it is a 
>> branch-and-price approach, where until now, branching decisions were 
>> handled by variable fixing (i.e., variables were fixed by the 
>> propagation callback of the corresponding constraint handler). 
>> However, I want to improve this branching, that is, in each child 
>> node I want to add multiple rows to the problem. Of course, I need to 
>> store these decisions to take them into consideration during variable 
>> pricing. (So, yet it is a branch-and-price-and-cut approach, but cuts 
>> are not added by separation procedure, but branching). I would like 
>> to ask, what is the best way to do that? (My best guess, is that in a 
>> branching rule I add the rows to the problem, and I also create a 
>> constraint sticked to child nodes. The corresponding constraint 
>> handler do nothing (may be propagation only), but could be used in 
>> variable pricing).
>>
>> Thanks, and best regards,
>> Marko
>>
>>
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