[Dip-tickets] [Dip] #24: doPriceCut gives infeasible when doCut and doRelaxCut solve

[Dip]

#24: doPriceCut gives infeasible when doCut and doRelaxCut solve
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Reporter:  mosu001  |       Type:  defect
  Status:  new      |   Priority:  major 
 Version:  0.8.7    |   Keywords:        
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Comment(by mgalati):

 Also, I noticed in trucks.py that you are not defining a subproblem (a
 relaxation). So, I am not sure how you plan to try and use PRICE_AND_CUT.
 In order to do PRICE_AND_CUT you must define some set of rows as a
 relaxation.

 Ok - now I am able to repeat what you are seeing for trucks.py. It starts
 in Phase I to generate an initial basis for the Dantzig-Wolfe
 reformulation. From this it attempts to generate new variables - but since
 the subproblem model is empty, it just returns the column of all 0's -
 which does not help to form an initial basis. So, it declares the problem
 infeasible.

 This is what I would expect. DIP does not know what to do in PRICE_AND_CUT
 when the user gives it no relaxation or subproblem. How do you plan to
 define your columns for this application? What you have currently cannot
 work.

 Matt

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Ticket URL: <https://projects.coin-or.org/Dip/ticket/24#comment:4>
Dip <https://projects.coin-or.org/Dip>
An extensible software framework for implementing decompositon-based bounding algorithms for use in solving large-scale discrete optimization problems.