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<small>John,<br>
<br>
Sorry for the delay of this reply.<br>
<br>
With the divesolves option the 'long problem' is not so long...! It is still longer than other equivalent problems but it's reasonable.</small><br>
<small>Furthermore, all my NRTs are done with this option without loss of performance.<br>
<br>
But, i have some questions for you:<br>
</small>
<ul>
<li><small>Using the divesolves option automatticaly enables the other dive options?</small>
</li><li><small>And, why using both divesolves and divingvectorlength extends the solving time (x2) ?</small>
</li><li><small>How can i finely choose the value of the divesolves option?<br>
</small></li></ul>
<p><small>Regards<br>
</small></p>
<p><small>Yves<br>
</small></p>
<b><br>
John Forrest</b> <a href="mailto:cbc%40list.coin-or.org?Subject=Re:%20Re%3A%20%5BCbc%5D%20Another%20problem%20%22long%20to%20be%20solved%22&In-Reply-To=%3C546B3584.9070306%40fastercoin.com%3E" title="[Cbc] Another problem "long to be solved"">
john.forrest at fastercoin.com </a><br>
<i>Tue Nov 18 07:03:16 EST 2014</i>
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<pre>Yves,
In trunk there are some new/modified options.
There was a parameter "experiment". I have left some old meanings, but
introduced some new ones. For difficult problems I would suggest
-experiment 3000 !!. This actually switches on multiple root solvers
(4), does more aggressive preprocessing, adds some extra root cut
generators AND switches on most diving heuristics.
When I tried, the code had no problems with long.lp, but I would suggest
you look at a new parameter divesolves. This can increase the number of
solves a diving heuristic can do. The bottom digit is ignored for
number of solves but can switch on something which could help you a
lot. Normally the diving heuristics fix some integer variables if they
are at their bound, however they do not fix satisfied general integer
variables - not at bound - so if 0 <= x <= 20 and x is at 12 then it
does not get fixed. I have allowed this behaviour to change so
-divesolves 301 will allow up to 300 solves and will fix some satisfied
general integers.
You may also want to look at diveoptions and even set -DDIVE_PRINT=1 in
configure. This switches on some printout which may help you understand
what is happening in which heuristic.
John
</pre>
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