A small LP that fail to solve

[luteberget]

Just started using HiGHS and very happy with it so far. Thanks!

I'm getting into some trouble with model status "Unknown" after optimizing, and wondering whether it could be a bug. I exported the problematic LP from a HiGHS instance into both .lp and .mps formats. Solving on the command line reproduces the issue when using the .mps file (but not the .lp file). Other solvers such as CBC and Gurobi report "Optimal" for both files.

Attaching the .mps file and the solver output.
test.mps.gz
highs.log.txt

[jajhall]

I've looked at this with detailed logging on, and see what's happening. Implementing a fix isn't difficult, but it's slightly scary, as it will change the behaviour of the simplex solver in a very small way <https://aka.ms/AAb9ysg>

…

________________________________ From: Bjørnar Steinnes Luteberget ***@***.***> Sent: Wednesday, October 30, 2024 12:04:09 PM To: ERGO-Code/HiGHS ***@***.***> Cc: Subscribed ***@***.***> Subject: [ERGO-Code/HiGHS] A small LP that fail to solve (Issue #2015) This email was sent to you by someone outside the University. You should only click on links or attachments if you are certain that the email is genuine and the content is safe. Just started using HiGHS and very happy with it so far. Thanks! I'm getting into some trouble with model status "Unknown" after optimizing, and wondering whether it could be a bug. I saved the problematic LP instances from a HiGHS instance into both .lp and .mps formats. Solving on the command line reproduces the issue when using the .mps file (but not the .lp file). Other solvers such as CBC and Gurobi report "Optimal" for both files. Attaching the .mps file and the solver output. test.mps.gz<https://github.com/user-attachments/files/17571965/test.mps.gz> highs.log.txt<https://github.com/user-attachments/files/17571968/highs.log.txt> — Reply to this email directly, view it on GitHub<#2015>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AFMWLY7HREU5GWRZ4XFIMATZ6DDLTAVCNFSM6AAAAABQ36JYZKVHI2DSMVQWIX3LMV43ASLTON2WKOZSGYZDGOBYGI3TGMI>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.***> The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. Is e buidheann carthannais a th’ ann an Oilthigh Dhùn Èideann, clàraichte an Alba, àireamh clàraidh SC005336.