[Couenne-tickets] [Couenne] #33: Counne says "tightened NLP is infeasible"

[Couenne]

#33: Counne says "tightened NLP is infeasible"
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  Reporter:  thofrei  |      Owner:  pbelotti
      Type:  defect   |     Status:  new
  Priority:  major    |  Milestone:
 Component:  Couenne  |    Version:
Resolution:           |   Keywords:  infeasible Couenne tightened NLP
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Comment (by pbelotti):

 Hi,

 the fact that no .sol file was produced suggests that infeasibility was
 proven at bound tightening, which is weird since the options I gave before
 turn off all bound tightening. You could try another option to relax the
 feasibility tolerance from 1e-6 to 1e-4, for instance:

 {{{
 feas_tolerance 1e-4
 }}}

 Finally, since Couenne only accepts .nl file I'm thinking that Pyomo must
 have a procedure to convert instances to that format. See for example

 https://projects.coin-
 or.org/Coopr/browser/coopr.pyomo/trunk/coopr/pyomo/scripting/convert.py?rev=9082

 If you could somewhat modify the source file to use the convert function
 and produce a .nl file, I would certainly be able to help more.

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Ticket URL: <https://projects.coin-or.org/Couenne/ticket/33#comment:5>
Couenne <https://projects.coin-or.org/Couenne>
Couenne, a solver for non-convex MINLP