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Ticket #4153 (new defect)

Opened 3 years ago

Last modified 2 years ago

Failure in glpk for infeasible problem

Reported by: wehart Owned by: wehart
Priority: major Milestone: Long Term
Component: coopr.solvers Version:
Keywords: Cc: kmhunte2@…, jwatson

Description

This is Example 2.3 in Rader's text. Not too worried about this one getting out.

If you change CrudeMax?[1] to 7000, which is asked in one of the problems, then the model is infeasible.

Thanks again. I will update everything once I get a chance to breath.

Attachments

Ex2.3.dat Download (505 bytes) - added by wehart 3 years ago.
Ex2.3.py Download (2.8 KB) - added by wehart 3 years ago.
RaderExample.zip Download (1.9 KB) - added by khunter 2 years ago.
Updated Ex.py to work with Coopr v3

Change History

Changed 3 years ago by wehart

Changed 3 years ago by wehart

comment:1 Changed 3 years ago by khunter

  • Cc kmhunte2@…, jwatson added

Th

comment:2 Changed 3 years ago by khunter

I committed a GLPK solver interface, glpk_experimental, in r3574 that should hopefully be a mite more robust. I think it's still missing a few details yet, but to be sure, it needs some folks other than myself to test it. I believe it will soon be able to replace the current GLPK solver interface.

With this problem, it correctly does not give a result for the 7000 version, but currently gives a status of "other" instead of "infeasible".

comment:3 Changed 3 years ago by wehart

  • Milestone changed from Coopr 2.x to Long Term

Changed 2 years ago by khunter

Updated Ex.py to work with Coopr v3

comment:4 Changed 2 years ago by khunter

Bill, you should sign off on this, but I believe the new GLPK solver resolves this issue. The attached zip file contains two files, Ex.py and 2.17.dat. I've updated Ex.py to work with Coopr v3 (function calls, basically), and made it slightly more user-friendly in that it can be run through pyomo or coopr_python now.

Uncomment line 7 in the dat file to showcase that the GLPK solver plugin now correctly handles the case of infeasibility.

(Also, I would add Allen's email address to the CC, but I don't know it ... if he doesn't already know about the updated GLPK solver plugin.)

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