Originally posted by: A.Omidi

Hello
I have a question on NP-Hard MILP/MINLP problems.
I read an article about "multi-server location-allocation problem in congested systems".
link: http://dx.doi.org/10.1016/j.cie.2014.03.018

In the solution section, the author said that "The constrained bi-objective non-linear mixed-integer programming problem modeled in Section 2 is strictly NP-Hard and exact methods cannot be used to solve it".
Please let me know, even on the small scale problem, do these models haven't the exact solution?

Best regards

I don't know the paper, nor the quote, nor the problem they are referring to. But in general I would agree that for NP hard problems, complete methods will work for very small instances or if you are willing to wait until the end of the universe.

I think you should rather check with the authors of the paper than with this forum.