[Dip-tickets] [Dip] #44: Infinite loop problem with DecompAlgoC

[Dip]

#44: Infinite loop problem with DecompAlgoC
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Reporter:  kmartin  |       Type:  defect
  Status:  new      |   Priority:  minor 
 Version:  trunk    |   Keywords:        
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 Hi:

 I have having trouble getting into an infinite loop at node 0 with
 DecompAlgoC. This problem seems to arise when a point in the core
 constraints in not in the relaxed polyhedron. Consider, for example,

 4*x1 + 9*x2 <= 18;
 -2*x1 +  4*x2 <= 4;
 x1 + x2 <=  2;

 Treat the third constraint as the core constraint. In this case
 DecompAlgoC works fine. Then change the RHS of the third constraint to 5
 and DecompAlgoC goes into an infinite loop at node 0 with

 Alps0240I Processed 0 nodes, has 1 nodes, best relaxed -5, best feasible
 1e+75
 Alps0240I Processed 0 nodes, has 1 nodes, best relaxed -5, best feasible
 1e+75
 Alps0240I Processed 0 nodes, has 1 nodes, best relaxed -5, best feasible
 1e+75
 Alps0240I Processed 0 nodes, has 1 nodes, best relaxed -5, best feasible
 1e+75
 Alps0240I Processed 0 nodes, has 1 nodes, best relaxed -5, best feasible
 1e+75


 repeated over and over.

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Ticket URL: <https://projects.coin-or.org/Dip/ticket/44>
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.