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Dear Abdelkader,<br>
<br>
in column generation, we are looking for improving variables, i.e.
variables with negative reduced cost (for minimization problems)
which the Simplex algorithm would enter into the basis. However, in
the pricing routine of column generation, we are only adding those
variables to the problem and are not adding them to the basis. After
those variables were added, the RMP will be re-optimized, and in
this course, the Simplex algorithm (if used) will decide on a column
to enter the basis and one to leave it (in each iteration, it might
need multiple ones to reach optimality again).<br>
<br>
Best,<br>
Gerald<br>
<br>
<div class="moz-cite-prefix">Am 05.12.2015 um 22:07 schrieb
Abdelkader Ouali:<br>
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<div dir="ltr"><font face="Calibri,sans-serif" color="#000000"
size="3">Hi scip community,</font>
<div><font face="Calibri,sans-serif" color="#000000" size="3"><br>
</font></div>
<div>
<div><font size="3">As column generation is based on simplex
algorithm,</font></div>
<div><font size="3">I want to know, why we need "</font><span
style="font-size: 12pt;">only"</span><span
style="font-size: 12pt;"> to enter a column into the
restricted master problem (RMP), and not to select a
column as an outgoing column after each solving of the RMP
relaxation?</span></div>
<div><font size="3">Thanks for any answer.</font></div>
</div>
<div><font size="3"><br>
</font></div>
<div><font size="3">Kind regards</font></div>
<div><font size="3">---</font></div>
<div><font size="3">A. Ouali</font></div>
</div>
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