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<div class="moz-cite-prefix">Dear Ahmed,<br>
<br>
the logic or, setppc, and varbound constraint handlers have
separation routines, but these only generates the linear rows
representing the specific constraints. They do not create 'real'
cutting planes.<br>
<br>
Remember that a constraint is not directly present in the LP, but
it will normally create one or more rows to add the constraint (or
a relaxation of it) to the LP. For linear constraints or their
specializations (e.g., logic or, setppc, and varbound), the
constraint can be represented by one linear row.<br>
If constraints have their 'initial' flag set to TRUE when created
(which is the default), the initial relaxation will be added to
the LP when building the LP data structure at the root node.
Linear constraints and specializations are then fully represented
in the LP and no separation is needed later, anymore.<br>
<br>
On the other hand, if 'initial' is set to FALSE or 'removable' to
TRUE, the row corresponding to a constraint may not be in the LP.
The separation procedure then checks whether the row would by
violated by the current LP solution and adds it, if needed. This
is similar to the concept of lazy constraints used in, e.g.,
CPLEX.<br>
<br>
Best,<br>
Gerald<br>
<br>
On 29.02.2016 20:51, Ahmed Ibrahim wrote:<br>
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<div style="direction: ltr;font-family: Tahoma;color:
#000000;font-size: 10pt;">Hi all,
<div>I was wondering if any one knows where can I find an
explanation of how cutting planes for logic or setppc and
varbound constraint handlers are obtained? </div>
<div><br>
</div>
<div>Regards,</div>
<div>Ahmed</div>
</div>
<br>
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