Re: [Help-glpk] presolving

[Andrew Makhorin]

> I have these two files that i attached
> 
> because when i fix these two files with GLPSOL, it used too long (even
> days) using the commands - math - cuts, and I wanted to know if there
> are ways of presolving to speed the resolution

Your mip has no feasible solution (see glpsol output below), so probably
you run some other instance, not that one you posted to the list. Please
note that even if your instance were feasible, I don't think that glpsol
could solve it for a reasonable time because of its very large size.

(prob.glp was generated from your model with the --wglp option)

GLPSOL: GLPK LP/MIP Solver, v4.48
Parameter(s) specified in the command line:
 --glp prob.glp --log log.txt
Reading problem data from `prob.glp'...
Problem: file25
Objective: z
43151 rows, 18000 columns, 4604913 non-zeros
18000 integer variables, all of which are binary
4687124 lines were read
GLPK Integer Optimizer, v4.48
43151 rows, 18000 columns, 4604913 non-zeros
18000 integer variables, all of which are binary
Preprocessing...
PROBLEM HAS NO PRIMAL FEASIBLE SOLUTION
Time used:   299.5 secs
Memory used: 293.9 Mb (308126836 bytes)

GLPSOL: GLPK LP/MIP Solver, v4.48
Parameter(s) specified in the command line:
 --nomip --glp prob.glp --log log.txt
Reading problem data from `prob.glp'...
Problem: file25
Objective: z
43151 rows, 18000 columns, 4604913 non-zeros
18000 integer variables, all of which are binary
4687124 lines were read
GLPK Simplex Optimizer, v4.48
43151 rows, 18000 columns, 4604913 non-zeros
Preprocessing...
PROBLEM HAS NO PRIMAL FEASIBLE SOLUTION
Time used:   57.7 secs
Memory used: 311.1 Mb (326187268 bytes)

GLPSOL: GLPK LP/MIP Solver, v4.48
Parameter(s) specified in the command line:
 --nomip --nopresol --glp prob.glp --log log.txt
Reading problem data from `prob.glp'...
Problem: file25
Objective: z
43151 rows, 18000 columns, 4604913 non-zeros
18000 integer variables, all of which are binary
4687124 lines were read
Scaling...
 A: min|aij| =  2.000e-02  max|aij| =  9.600e+03  ratio =  4.800e+05
GM: min|aij| =  2.207e-01  max|aij| =  4.531e+00  ratio =  2.053e+01
EQ: min|aij| =  4.886e-02  max|aij| =  1.000e+00  ratio =  2.047e+01
Constructing initial basis...
Size of triangular part = 36851
GLPK Simplex Optimizer, v4.48
43151 rows, 18000 columns, 4604913 non-zeros
      0: obj =   9.000000000e+03  infeas =  7.099e+02 (6300)
    500: obj =   9.000000000e+03  infeas =  2.339e+02 (6300)
   1000: obj =   9.000000000e+03  infeas =  5.366e+01 (6300)
   1327: obj =   9.000000000e+03  infeas =  5.985e+00 (6300)
PROBLEM HAS NO FEASIBLE SOLUTION
Time used:   118.6 secs
Memory used: 345.1 Mb (361818021 bytes)