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Dear Christina,<br>
<br>
sorry for the late reply, but we were quite busy in the last weeks.<br>
<br>
There might be different reasons for this behavior.<br>
<br>
1) Does your pricing callback compute a lower bound and sets the
lowerbound pointer accordingly? If this is higher than the cutoff
bound, the node will be cut off.<br>
<br>
2) Perhaps the propagation already detected infeasibility? Are you
sure that you perform pricing at this node?<br>
<br>
3) Are all your variables created by pricing and all constraints
marked to be modifiable? Otherwise, the enforcement might also
detect infeasibility of an unmodifiable constraint.<br>
<br>
Best,<br>
Gerald<br>
<br>
<div class="moz-cite-prefix">Am 19.02.2015 um 15:27 schrieb Cristina
Núñez del Toro:<br>
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<div>Dear all,<br>
<br>
</div>
I am currently implemented a Branch&Price
algorithm. For my problem, I have 3 types of
variables, say "x","y" and "z". I have just finished
my on branching rule that implies to only branch on
the "z" variables. Apparently, everything goes ok; I
mean, everytime SCIP enters to the branchexeclp
routine, it looks for the most fractional "z"
variable and do branch on it. However, I have
noticed that a certain point of the algorithm, after
finishing the pricing loop, SCIP "skips" (sorry for
the joke) the branching phase (the node is cutted
off/pruned), I mean, it does not enter to any
branching callback method and goes directly to the
handler constraint to propagate another node. As far
I understand, this would be of course a normal
behaviour if, after finishing the pricing stage :<br>
<br>
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a) the objective value of the current LP is greater or
equal than the incumbent,<br>
b) the current LP solution is an integer solution,<br>
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c) the current LP solution is an integer solution and it
is optimal.<br>
<br>
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However, I found a pruned node with a fractional LP
solution (inluding some "z" variables with fractional
value) but with the objective value <span id="result_box"
class="" lang="en"><span class="">strictly lower than
the incumbent.<br>
<br>
</span></span></div>
<span id="result_box" class="" lang="en"><span class="">Is
there any reason for expecting this? <br>
<br>
</span></span></div>
<span id="result_box" class="" lang="en"><span class="">Thanks
in advances,<br>
<br>
</span></span></div>
<span id="result_box" class="" lang="en"><span class="">Best
regards,<br>
</span></span>
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<br>
-- <br>
<div class="gmail_signature">---<br>
Cristina Nuñez<br>
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