option cplex_options 'mipdisplay 2 mipinterval 1000';
(or add these directives to a cplex_options string that you're already
using) then the resulting log should give some more useful information about
what's causing the problem. For further help you may want to post the
entire log.
Bob Fourer
4...@ampl.com
Here's the output (I skipped a big part and wrote [...]) :
IBM ILOG License Manager: "IBM ILOG Optimization Suite for Academic
Initiative" is accessing CPLEX 12 with option(s): "e m b q ".
CPLEX 12.2.0.0: mipdisplay 2
mipinterval 1000
MIP Presolve eliminated 1560 rows and 30 columns.
MIP Presolve modified 3640 coefficients.
Reduced MIP has 10593 rows, 3183 columns, and 32534 nonzeros.
Reduced MIP has 2172 binaries, 0 generals, 0 SOSs, and 0 indicators.
Probing time = 0.01 sec.
Probing time = 0.01 sec.
Clique table members: 2721.
MIP emphasis: balance optimality and feasibility.
MIP search method: dynamic search.
Parallel mode: deterministic, using up to 32 threads.
Root relaxation solution time = 1.29 sec.
Nodes Cuts/
Node Left Objective IInf Best Integer Best Node ItCnt
Gap
0 0 0.0000 376 0.0000 9
0 0 0.0000 480 Cuts: 1359 760
0 0 0.0000 488 Cuts: 273 1454
0 2 0.0000 369 0.0000 1521
Elapsed real time = 11.35 sec. (tree size = 0.01 MB)
* 566+ 344 1.4200 0.0000 85844
100.00%
* 566+ 229 1.4160 0.0000 85844
100.00%
* 575+ 158 1.3800 0.0000 89166
100.00%
* 577+ 109 1.0800 0.0000 89649
100.00%
* 577+ 76 1.0741 0.0000 89649
100.00%
* 590+ 61 0.8360 0.0000 93967
100.00%
* 590+ 47 0.7906 0.0000 93967
100.00%
* 590+ 38 0.7876 0.0000 93967
100.00%
1000 405 0.0000 300 0.7876 0.0000 157035
100.00%
2000 1337 0.0400 278 0.7876 0.0000 311991
100.00%
* 2356+ 1602 0.7859 0.0000 345905
100.00%
* 2356+ 1602 0.7110 0.0000 345905
100.00%
3000 2215 0.0000 295 0.7110 0.0000 381054
100.00%
4000 3065 0.0200 192 0.7110 0.0000 463947
100.00%
5000 3865 0.0400 318 0.7110 0.0000 545310
100.00%
6000 4568 0.3050 226 0.7110 0.0000 593454
100.00%
* 6378+ 4788 0.3233 0.0000 601247
100.00%
* 6378+ 4788 0.3217 0.0000 601247
100.00%
* 6378+ 4788 0.2800 0.0000 601247
100.00%
* 6378+ 4788 0.2500 0.0000 601247
100.00%
7000 5246 0.0000 268 0.2500 0.0000 636107
100.00%
* 7540+ 5575 0.2344 0.0000 665479
100.00%
8000 5874 0.0000 186 0.2344 0.0000 691026
100.00%
9000 5729 0.0000 183 0.2344 0.0000 725217
100.00%
10000 6329 0.0000 188 0.2344 0.0000 774956
100.00%
Elapsed real time = 124.81 sec. (tree size = 1.64 MB)
11000 6932 0.0813 319 0.2344 0.0000 825896
100.00%
[...]
Elapsed real time = 24200.60 sec. (tree size = 8554.09 MB)
Nodefile size = 8425.47 MB (2148.18 MB after compression)
4631000 2877304 0.0676 253 0.1000 0.0000
3.25e+08 100.00%
4632000 2877972 0.0330 223 0.1000 0.0000
3.26e+08 100.00%
4633000 2878625 0.0840 166 0.1000 0.0000
3.26e+08 100.00%
4634000 2879293 0.0170 171 0.1000 0.0000
3.26e+08 100.00%
4635000 2879913 infeasible 0.1000 0.0000
3.26e+08 100.00%
4636000 2880567 0.0252 195 0.1000 0.0000
3.26e+08 100.00%
4637000 2881197 0.0773 199 0.1000 0.0000
3.26e+08 100.00%
4638000 2881827 0.0900 132 0.1000 0.0000
3.26e+08 100.00%
4639000 2882463 0.0640 162 0.1000 0.0000
3.26e+08 100.00%
4640000 2883095 0.0882 81 0.1000 0.0000
3.26e+08 100.00%
Elapsed real time = 24358.31 sec. (tree size = 8576.43 MB)
Nodefile size = 8447.44 MB (2153.76 MB after compression)
4641000 2883729 0.0918 300 0.1000 0.0000
3.26e+08 100.00%
4642000 2884365 infeasible 0.1000 0.0000
3.26e+08 100.00%
4643000 2884928 0.0700 165 0.1000 0.0000
3.26e+08 100.00%
4644000 2885526 0.0950 107 0.1000 0.0000
3.26e+08 100.00%
4644000 2885526 0.0950 107 0.1000 0.0000
3.26e+08 100.00%
error running cplexamp:
termination code 9
<BREAK>
That's all I get. The computer on which this is run has 256 Gigabytes of
RAM.
Any idea ?
Patrick
In general this does not look like a promising run, as the lower bound never
rises above zero, and for every 1000 nodes explored only about 400 are
fathomed while 600 are added to the tree for further processing. There's no
end in sight. It might be worth investigating how it is that solutions to
the linear relaxation can have an objective of zero, and whether cuts can be
added to raise that value. Also CPLEX has many algorithmic options for
integer programming (see chapter 7 of
www.ampl.com/BOOKLETS/amplcplex122userguide.pdf) and for a very hard problem
it can be worth experimenting with changes to some of the default settings.
Bob Fourer
4...@ampl.com
https://www-304.ibm.com/support/docview.wss?dc=D400&rs=539&uid=swg24028951&c
ontext=SSC5SPS&cs=utf-8&lang=en&loc=en_US
In fact there is a new version 12.3 of CPLEX for which we have AMPL support,
but I'm not sure it is available yet through the IBM Academic Initiative.
If you want to send me some files I will try running your model under 12.3
to see what happens (though I have access to only 12GB of RAM). (I can also
try applying Gurobi to it.)
For a stubborn CPLEX problem you also have the option of posting to one of
the IBM ILOG Optimization Forums; see
http://www.ibm.com/developerworks/forums/category.jspa?categoryID=260
This puts you in touch with the CPLEX developers. If in AMPL you specify,
say,
option cplex_options 'writeprob paterijk.sav';
(or add this directive to any cplex_options string you're currently
specifying) then CPLEX will write your problem in ".sav" format which may be
helpful to the CPLEX people (though it may also help them to see your AMPL
model).
Bob Fourer
4...@ampl.com
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Nodes Cuts/
Node Left Objective IInf Best Integer Best Node ItCnt
Gap
0 0 0.0000 376 0.0000 9
0 0 0.0000 480 Cuts: 1359 760
0 0 0.0000 488 Cuts: 273 1454
0 2 0.0000 369 0.0000 1521
SOLVING ...
CPLEX 12.9.0.0: mipdisplay 2
mipinterval 1
symmetry 5
presolve 1
nodefile 3
1 of 1 MIP starts provided solutions.
MIP start 'm1' defined initial solution with objective 6589.6287.
MIP Presolve eliminated 411378 rows and 291444 columns.
MIP Presolve modified 4051048 coefficients.
Reduced MIP has 1171990 rows, 376474 columns, and 65665842 nonzeros.
Reduced MIP has 376350 binaries, 0 generals, 0 SOSs, and 0 indicators.
Probing time = 13.51 sec. (2689.34 ticks)
Cover probing fixed 2 vars, tightened 0 bounds.
MIP Presolve eliminated 0 rows and 2 columns.
Reduced MIP has 1171990 rows, 376472 columns, and 65665828 nonzeros.
Reduced MIP has 376348 binaries, 0 generals, 0 SOSs, and 0 indicators.
Probing fixed 1 vars, tightened 0 bounds.
Probing time = 8.96 sec. (2182.68 ticks)
Clique table members: 11538889.
MIP emphasis: balance optimality and feasibility.
MIP search method: dynamic search.
Parallel mode: deterministic, using up to 16 threads.
error running cplex:
termination code 9
<BREAK>
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