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

[Horváth Markó]

Hi,

if I set it to TRUE, also nothing is happened. Should I use the callback 
scip_active for this purpose? Anyway, which is the best way to add new 
rows to the problem for branching purpose?

Best regards,
Marko

2022. 06. 20. 8:44 keltezéssel, Gerald Gamrath írta:
> 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
>>>
>>>
>>> _______________________________________________
>>> Scip mailing list
>>> Scip at zib.de
>>> https://listserv.zib.de/mailman/listinfo/scip
>>
-- 
Markó HORVÁTH PhD,
research fellow
-------------------------------------------------------------
Research Laboratory on Engineering & Management Intelligence,
Institute for Computer Science and Control
  H-1111 Budapest, Kende u. 13-17.
  Room : K318
  Phone: +36 1 279 7164