
From:  Joey Rios 
Subject:  [Helpglpk] Using branch and cut starting with relaxed solution 
Date:  Wed, 17 Dec 2008 09:37:25 0800 
I know this has been asked in different ways, but I haven't gotten a clear sense of what to do from those previous posts. I have a relaxed solution to a binary integer program. In most of my cases, well over 90% of the variables are already binary. I'd like to use the branch and bound/cut code already in GLPK to get to an integer solution. The main problem I have is that I didn't arrive at the relaxed solution through a standard glp_simplex() call, so I don't have a basis ready, else I'd just call glp_intopt() and see what happens. So I guess I have a few questions: 1. What would be the method for creating a basis in this case? I assume all of the binary variables with nonbinary values would need to be basic, but after that how do I decide which other variables are basic just given their values from my relaxed solution? 2. I have the reference manual for version 4.34 in front of me. Should/can I just use the branchandcut API directly somehow? If so, how should I go about using my relaxed solution as a starting point? 3. Given what I've described, is there something else I should try? Any advice appreciated. I can provide further details if they'd be helpful. Thanks. Suspicious message? There’s an alert for that. Get your Hotmail® account now. 
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