<div dir="ltr"><div>Thank you very much John for your kind assistance :)<br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-07-01 15:10 GMT+02:00 John Forrest <span dir="ltr"><<a href="mailto:john.forrest@fastercoin.com" target="_blank">john.forrest@fastercoin.com</a>></span>:<br>
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<div>Marco,<br>
<br>
There was an option to try heuristics even if it looked
unpromising. I have modified code so that if this is set then
heuristics do not get switched off even if unknown branching
objects.<br>
<br>
When I did this code entered heuristics, but feasibility pump
decided it wasn't worth it on your tiny problem (too high a
proportion of general integer variables). There was a way to tell
that particular heuristic to carry on. You can see the way that
was set in attached sample.<br>
<br>
It should all be safe - although it is possible an heuristic may
get a solution which is then thrown out on closer inspection - but
that's OK.<br>
<br>
John Forrest<div><div class="h5"><br>
On 01/07/14 11:06, mg wrote:<br>
</div></div></div>
<blockquote type="cite"><div><div class="h5">
<div dir="ltr">Hi All,
<div>I'm currently solving a complex (lot-sizing like) problem
where some variables are semi-continuous in the sense that
they're zero or greater than a certain threshold.</div>
<div><br>
</div>
<div>Of course this discontinuity can be implemented either
using a binary variable or using a CbcLotSize branching
object, with the latter being theoretically more efficient
than the former.</div>
<div><br>
</div>
<div>Problem is, if I introduce a LotSize object, this
automatically disable all the heuristics (I'm solving the
problem through CallCBC) since they do not support objects
other than integers or SOS...</div>
<div><br>
</div>
<div>But as I said the problem is complex, the time to solve it
is limited and the heuristics usually greatly help in finding
the best solution.</div>
<div><br>
</div>
<div>Do you have any suggestion on how to work around this issue
? </div>
<div>Should I introduce a binary variable instead of the branch
object ?<br>
</div>
<div><br>
</div>
<div>Thanks in advance,</div>
<div>Marco</div>
<div><br>
</div>
<div>P.S.</div>
<div>I'm using CBC trunk</div>
<div><br>
</div>
<div><br>
</div>
</div>
<br>
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