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[Help-glpk] Asking explanation on glpsol screen messages


From: john tass
Subject: [Help-glpk] Asking explanation on glpsol screen messages
Date: Sat, 28 Mar 2015 14:19:50 +0200

Good day,
I face a minimization problem for which I know a-priori that its optimum objective function value is 0 (zero) (As a matter of fact I have solved the problem via heuristics methods). Now, I want to solve the same problem via glpsol (command line). I have modeled the problem with Mathprog modeling language and I have provided a dat file. Please note that the program concerns a discrete space, therefore the  variables have to take 0-1 values. When I run the glpsol from command line, I get a message saying that lp problem solved and there is a feasible solution. Then, it proceeds to the solution of IP. During the run, I get the following messages:
"time used 1472 sec memory used 131Mb
mip = not found yet >= 5.27 e-17
mip = not found yet >= 5.27 e-17
mip = not found yet >= 5.27 e-17
....
....
mip = not found yet >= 5.27 e-17

obj = 2e-1 infease = 4.387 e-15
obj = 2e-1 infease = 4.387 e-15
obj = 2e-1 infease = 4.387 e-15"

then again:

"mip = not found yet >= 5.27 e-17
mip = not found yet >= 5.27 e-17
mip = not found yet >= 5.27 e-17"

At some point it was displayed:

"warning : dual degeneracy : switching to primal simplex"
Then it continues displaying similar messages like :
"time used 2000 sec memory used 131Mb
mip = not found yet >= 5.27 e-17
mip = not found yet >= 5.27 e-17
mip = not found yet >= 5.27 e-17
....
....
mip = not found yet >= 5.27 e-17"

I must admit that I can not understand almost anything.
Can anyone give me an explanation of what all these messages mean?
Can anyone tell me in a few words what is happenning with my application?
In addition, is there any source that I can get some information about the above terms, like " infease", " dual degeneracy", "primal simplex"?
Thank you very much for your time and excuse my questions that may be too simple...



--
Ioannis X. Tassopoulos

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