Re: [Help-glpk] Modelling Advice Request - Project Tasks

[Andrew Makhorin]

> I #39;m not sure I #39;m getting correct answers.  For the t65d11xx
> problem with gmpl code I got an objective
> value of 283,971 where the claim is that the best known value is
> 237,739.  I #39;m curious what you
> found for an objective value for this example.

I run your model for t65d11xx with glpsol v4.42 and also got the correct
solution:

GLPSOL: GLPK LP/MIP Solver, v4.42
Parameter(s) specified in the command line:
 -m lop --log log
Reading model section from lop...
Reading data section from lop...
238 lines were read
Generating savings...
Generating c1...
Generating c2...
Model has been successfully generated
glp_mpl_build_prob: row savings; constant term 115797 ignored
GLPK Integer Optimizer, v4.42
26489 rows, 946 columns, 80192 non-zeros
946 integer variables, all of which are binary
Preprocessing...
26488 hidden covering inequaliti(es) were detected
52976 rows, 946 columns, 158928 non-zeros
946 integer variables, all of which are binary
Scaling...
 A: min|aij| =  1.000e+00  max|aij| =  1.000e+00  ratio =  1.000e+00
Problem data seem to be well scaled
Constructing initial basis...
Size of triangular part = 52976
Solving LP relaxation...
GLPK Simplex Optimizer, v4.42
52976 rows, 946 columns, 158928 non-zeros
*     0: obj =   1.157970000e+05  infeas =  0.000e+00 (0)
*   500: obj =   2.292050000e+05  infeas =  5.551e-14 (0)
*  1000: obj =   2.516573333e+05  infeas =  3.429e-14 (0)
*  1500: obj =   2.670560000e+05  infeas =  8.466e-13 (0)
*  2000: obj =   2.698580000e+05  infeas =  1.060e-12 (0)
*  2500: obj =   2.773320000e+05  infeas =  1.618e-12 (0)
*  3000: obj =   2.800900000e+05  infeas =  8.661e-13 (0)
*  3500: obj =   2.817750000e+05  infeas =  1.996e-12 (0)
*  4000: obj =   2.830760000e+05  infeas =  1.178e-12 (0)
*  4500: obj =   2.835170000e+05  infeas =  1.703e-12 (0)
*  5000: obj =   2.835170000e+05  infeas =  8.302e-13 (0)
*  5500: obj =   2.838870000e+05  infeas =  1.055e-12 (0)
*  6000: obj =   2.839320000e+05  infeas =  1.701e-12 (0)
*  6500: obj =   2.839690000e+05  infeas =  1.691e-12 (0)
*  6782: obj =   2.839710000e+05  infeas =  1.489e-12 (0)
OPTIMAL SOLUTION FOUND
Integer optimization begins...
+  6782: mip =     not found yet <=              +inf        (1; 0)
+  6787: >>>>>   2.839710000e+05 <=   2.839710000e+05   0.0% (1; 0)
+  6787: mip =   2.839710000e+05 <=     tree is empty   0.0% (0; 1)
INTEGER OPTIMAL SOLUTION FOUND
Time used:   85.3 secs
Memory used: 53.9 Mb (56510270 bytes)

(There is a glitch in v4.42 which has been fixed in v4.43: the mip
preprocessor discovers hidden packing inequality constraints, however,
original constraints are not removed, so the number of rows is doubled.
This, of course, does not affect the solution.)