Questions Tagged With cutoffhttp://www.or-exchange.com/tags/cutoff/?type=rssquestions tagged <span class="tag">cutoff</span>enWed, 18 Apr 2018 09:52:04 -0400RINS Cutoff does not let CPLEX trigger Solution Polishinghttp://www.or-exchange.com/questions/15572/rins-cutoff-does-not-let-cplex-trigger-solution-polishing<p><strong>Context:</strong> I am trying to solve a hard MIP problem for which I want to apply RINS in the first phase of solve (for about 30 minutes) and then apply Solution Polishing. </p>
<p><strong>Problem:</strong> However, when the cutoff time for solution polishing is reached, I see a cutoff in the log file and the optimization stops even though the gap is very high. This does not happen if I remove RINS. I suspect this happens because RINS sets the objective cutoff based on objective value of the current incumbent. I am pasting the solver log below for reference.</p>
<p><strong>Question:</strong> Is there a way of being able to use RINS and polishing both in a same run, with RINS running in phase 1 and polishing in phase 2 without stopping the optimization?
</p><pre>LOG
Found incumbent of value -1.8400260e+09 after 1497.56 sec. (506818.92 ticks)
* 0+ 0 -6.22229e+08 -5082567.9764 99.18%
Found incumbent of value -6.2222884e+08 after 1663.41 sec. (555865.80 ticks)
0 0 cutoff -6.22229e+08 -5082567.9764 101011 99.18%
Elapsed time = 1801.08 sec. (599903.47 ticks, tree = 0.01 MB, solutions = 15)<p></p>
<p>Starting condition for polishing reached (PolishAfterTime).
Starting solution polishing.</p>
<p>Clique cuts applied: 53
Cover cuts applied: 226
Implied bound cuts applied: 790
Flow cuts applied: 2475
Mixed integer rounding cuts applied: 3183
Flow path cuts applied: 258
Zero-half cuts applied: 74
Gomory fractional cuts applied: 23</p>
<p>Root node processing (before b&c):
Real time = 1801.92 sec. (600049.86 ticks)
Parallel b&c, 32 threads:
Real time = 6.08 sec. (128.66 ticks)
Sync time (average) = 0.06 sec.
Wait time (average) = 1.97 sec.
------------
Total (root+branch&cut) = 1808.00 sec. (600178.52 ticks)</p>
<p>Solution pool: 15 solutions saved.</p>
<p>MIP - Integer optimal solution: Objective = -6.2222884063e+08
Solution time = 1808.03 sec. Iterations = 101011 Nodes = 0
Deterministic time = 600181.79 ticks (331.95 ticks/sec)
</p></pre><p></p>AMIT_HOODAWed, 18 Apr 2018 09:52:04 -0400http://www.or-exchange.com/questions/15572/rins-cutoff-does-not-let-cplex-trigger-solution-polishingpolishingcutoffsolutionrins