<div dir="ltr"><div>First short: you do not generate "all" columns, that is, your pricing problem is buggy. Check whether you calculate reduced costs correctly, check whether your pricing problem formulation is correct, verify with toy examples that you can (and do) solve by hand for comparison.<br>
<br></div>Bests,<br>Marco<br><br></div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/8/6 Mahdi Noorizadegan (DIMAP) <span dir="ltr"><<a href="mailto:phd09mn@mail.wbs.ac.uk" target="_blank">phd09mn@mail.wbs.ac.uk</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div><div><div>Dear SCIP,<br><br></div>I am trying to solve a variant of VRP in SCIP within branch and price algorithms.<br>
</div>The problem is that after few iterations without any dual bound and infinite gap, it generates a lower bound which is higher than the optimal solution of the instance I solve. <br>
</div>I was wondering if you could help me to understand how SCIP generates the dual bound and why while it is still in early stages it generates very high lower bound?<br><br></div>Thanks<span class="HOEnZb"><font color="#888888"><br>
</font></span></div><span class="HOEnZb"><font color="#888888">Mahdi<br></font></span></div>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Prof. Dr. Marco Lübbecke<br>RWTH Aachen University <br>Chair of Operations Research <br>Kackertstrasse 7 <br>D-52072 Aachen <br>
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