Just to provide the result of another solver:<br><br>GLPK 4.39 quickly says that the problem is UNBOUNDED :<br><br>glpsol --cpxlp --intopt --cuts subProb.n0.c0.p3.b2.lp <br>GLPSOL: GLPK LP/MIP Solver 4.39<br>Reading problem data from `subProb.n0.c0.p3.b2.lp'...<br>
293 rows, 861 columns, 665 non-zeros<br>366 integer variables, 60 of which are binary<br>1337 lines were read<br>ipp_basic_tech: 0 row(s) and 720 column(s) removed<br>ipp_reduce_bnds: 2 pass(es) made, 80 bound(s) reduced<br>
ipp_basic_tech: 0 row(s) and 0 column(s) removed<br>ipp_reduce_coef: 1 pass(es) made, 0 coefficient(s) reduced<br>glp_intopt: presolved MIP has 293 rows, 141 columns, 665 non-zeros<br>glp_intopt: 61 integer columns, 60 of which are binary<br>
Scaling...<br> A: min|aij| = 1.670e-01 max|aij| = 1.250e+02 ratio = 7.485e+02<br>GM: min|aij| = 1.275e-01 max|aij| = 7.845e+00 ratio = 6.155e+01<br>EQ: min|aij| = 1.625e-02 max|aij| = 1.000e+00 ratio = 6.155e+01<br>
2N: min|aij| = 1.044e-02 max|aij| = 1.604e+00 ratio = 1.537e+02<br>Constructing initial basis...<br>Size of triangular part = 293<br>Solving LP relaxation...<br>* 0: obj = 0.000000000e+00 infeas = 0.000e+00 (0)<br>
* 2: obj = 0.000000000e+00 infeas = 0.000e+00 (0)<br>PROBLEM HAS UNBOUNDED SOLUTION<br>Time used: 0.0 secs<br>Memory used: 0.5 Mb (510288 bytes)<br><br><br><div class="gmail_quote">On Thu, Jul 30, 2009 at 11:34 PM, Matthew Galati <span dir="ltr"><<a href="mailto:magh@lehigh.edu">magh@lehigh.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Cplex and CBC are giving completely different results on this one. I don't think this problem is infeasible or unbounded - so I think it might be a CBC bug.<br>
<br><a href="http://coral.ie.lehigh.edu/%7Emagh/tmp/subProb.n0.c0.p3.b2.lp" target="_blank">http://coral.ie.lehigh.edu/~magh/tmp/subProb.n0.c0.p3.b2.lp</a><br>
<br><br><br>Problem 'subProb.n0.c0.p3.b2.lp' read.<br>Read time = 0.00 sec.<br>CPLEX> opt<br>Tried aggregator 1 time.<br>MIP Presolve eliminated 290 rows and 843 columns.<br>Reduced MIP has 3 rows, 3 columns, and 6 nonzeros.<br>
Presolve time = 0.00 sec.<br>Clique table members: 1.<br>MIP emphasis: balance optimality and feasibility.<br>Root relaxation solution time = 0.00 sec.<br><br>MIP - Integer optimal solution: Objective = -7.4380291900e+03<br>
Solution time = 0.00 sec. Iterations = 0 Nodes = 0<br><br><br><br><br><br><br><br>Coin Cbc and Clp Solver version 2.30.00, build Dec 1 2008<br>command line - ./bin/cbc /users/magala/subProb.n0.c0.p3.b2.lp (default strategy 1)<br>
### WARNING: CoinLpIO::readLp(): Variable x(1) does not appear in objective function or constraints<br>### WARNING: CoinLpIO::readLp(): Variable x(7) does not appear in objective function or constraints<br>### WARNING: CoinLpIO::readLp(): Variable x(133) does not appear in objective function or constraints<br>
### WARNING: CoinLpIO::readLp(): Variable x(139) does not appear in objective function or constraints<br>### WARNING: CoinLpIO::readLp(): Variable x(145) does not appear in objective function or constraints<br>### WARNING: CoinLpIO::readLp(): Variable x(151) does not appear in objective function or constraints<br>
### WARNING: CoinLpIO::readLp(): Variable x(157) does not appear in objective function or constraints<br>### WARNING: CoinLpIO::readLp(): Variable x(163) does not appear in objective function or constraints<br>### WARNING: CoinLpIO::readLp(): Variable x(169) does not appear in objective function or constraints<br>
### WARNING: CoinLpIO::readLp(): Variable x(175) does not appear in objective function or constraints<br>### WARNING: CoinLpIO::readLp(): Variable x(393) does not appear in objective function or constraints<br>### WARNING: CoinLpIO::readLp(): Variable x(396) does not appear in objective function or constraints<br>
### WARNING: CoinLpIO::readLp(): Variable x(409) does not appear in objective function or constraints<br>### WARNING: CoinLpIO::readLp(): Variable x(472) does not appear in objective function or constraints<br>### WARNING: CoinLpIO::readLp(): Variable x(487) does not appear in objective function or constraints<br>
Coin0508I Presolve thinks problem is unbounded<br>Continuous objective value is -1.16003e+14 - 0.00 seconds<br>Coin0508I Presolve thinks problem is unbounded<br>Cgl0000I Cut generators found to be infeasible!<br>Pre-processing says infeasible or unbounded<br>
Total time 0.02<br><br>
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<br></blockquote></div><br><br clear="all"><br>-- <br>=============================================================<br>Haroldo Gambini Santos<br>Computing Department - Universidade Federal de Ouro Preto - UFOP<br>email: <a href="mailto:haroldo.santos@gmail.com">haroldo.santos@gmail.com</a><br>
home/research page: <a href="http://www.ic.uff.br/~hsantos/">http://www.ic.uff.br/~hsantos/</a><br><br>“BE the change you want to see in the world” -Mahatma Gandhi<br><br>