[PPL-devel] Variables erroneously read as binary?
Roberto Bagnara
bagnara at cs.unipr.it
Sat Jan 9 11:02:54 CET 2010
After an upgrade to Fedora 12 (which ships GLPK 4.40) the attached
MPS is interpreted as having all binary variables:
$ glpsol --min ~/ppl/ppl/demos/ppl_lpsol/examples/ex1.mps
GLPSOL: GLPK LP/MIP Solver 4.40
Parameter(s) specified in the command line:
--min /home/roberto/ppl/ppl/demos/ppl_lpsol/examples/ex1.mps
Reading problem data from `/home/roberto/ppl/ppl/demos/ppl_lpsol/examples/ex1.mps'...
Problem: from_lp_file
Objective: r_000000
3 rows, 2 columns, 6 non-zeros
2 integer variables, all of which are binary
19 records were read
ipp_basic_tech: 3 row(s) and 2 column(s) removed
ipp_reduce_bnds: 1 pass(es) made, 0 bound(s) reduced
ipp_basic_tech: 0 row(s) and 0 column(s) removed
ipp_reduce_coef: 1 pass(es) made, 0 coefficient(s) reduced
Objective value = -2
INTEGER OPTIMAL SOLUTION FOUND BY MIP PRESOLVER
Time used: 0.0 secs
Memory used: 0.0 Mb (45508 bytes)
On Fedora 10 (which ships GLPK 4.36) the same file is interpreted
as having no binary variables:
$ glpsol --min ~/ppl/ppl/demos/ppl_lpsol/examples/ex1.mps
glp_read_mps: reading problem data from `/home/bagnara/ppl/ppl/demos/ppl_lpsol/examples/ex1.mps'...
glp_read_mps: problem from_lp_file
glp_read_mps: 3 rows, 2 columns, 6 non-zeros
glp_read_mps: 2 integer columns, none of which are binary
glp_read_mps: 19 records were read
ipp_basic_tech: 1 row(s) and 0 column(s) removed
ipp_reduce_bnds: 2 pass(es) made, 2 bound(s) reduced
ipp_basic_tech: 0 row(s) and 0 column(s) removed
ipp_reduce_coef: 1 pass(es) made, 0 coefficient(s) reduced
glp_intopt: presolved MIP has 2 rows, 2 columns, 4 non-zeros
glp_intopt: 2 integer columns, none of which are binary
Scaling...
A: min|aij| = 1.000e+00 max|aij| = 4.000e+00 ratio = 4.000e+00
Problem data seem to be well scaled
Crashing...
Size of triangular part = 2
Solving LP relaxation...
* 0: obj = 0.000000000e+00 infeas = 0.000e+00 (0)
* 2: obj = -3.750000000e+00 infeas = 0.000e+00 (0)
OPTIMAL SOLUTION FOUND
Integer optimization begins...
+ 2: mip = not found yet >= -inf (1; 0)
+ 4: >>>>> -3.000000000e+00 >= -3.000000000e+00 0.0% (2; 0)
+ 4: mip = -3.000000000e+00 >= tree is empty 0.0% (0; 3)
INTEGER OPTIMAL SOLUTION FOUND
Time used: 0.0 secs
Memory used: 0.1 Mb (84145 bytes)
[bagnara at spartacus ppl_lpsol]$ rpm -q glpsol
package glpsol is not installed
[bagnara at spartacus ppl_lpsol]$ qpm -k glpk-utils
-bash: qpm: command not found
[bagnara at spartacus ppl_lpsol]$ rpm -q glpk-utils
glpk-utils-4.36-1.fc10.x86_64
[bagnara at spartacus ppl_lpsol]$
[bagnara at spartacus ppl_lpsol]$ glpsol --min ~/ppl/ppl/demos/ppl_lpsol/examples/ex1.mps
glp_read_mps: reading problem data from `/home/bagnara/ppl/ppl/demos/ppl_lpsol/examples/ex1.mps'...
glp_read_mps: problem from_lp_file
glp_read_mps: 3 rows, 2 columns, 6 non-zeros
glp_read_mps: 2 integer columns, none of which are binary
glp_read_mps: 19 records were read
ipp_basic_tech: 1 row(s) and 0 column(s) removed
ipp_reduce_bnds: 2 pass(es) made, 2 bound(s) reduced
ipp_basic_tech: 0 row(s) and 0 column(s) removed
ipp_reduce_coef: 1 pass(es) made, 0 coefficient(s) reduced
glp_intopt: presolved MIP has 2 rows, 2 columns, 4 non-zeros
glp_intopt: 2 integer columns, none of which are binary
Scaling...
A: min|aij| = 1.000e+00 max|aij| = 4.000e+00 ratio = 4.000e+00
Problem data seem to be well scaled
Crashing...
Size of triangular part = 2
Solving LP relaxation...
* 0: obj = 0.000000000e+00 infeas = 0.000e+00 (0)
* 2: obj = -3.750000000e+00 infeas = 0.000e+00 (0)
OPTIMAL SOLUTION FOUND
Integer optimization begins...
+ 2: mip = not found yet >= -inf (1; 0)
+ 4: >>>>> -3.000000000e+00 >= -3.000000000e+00 0.0% (2; 0)
+ 4: mip = -3.000000000e+00 >= tree is empty 0.0% (0; 3)
INTEGER OPTIMAL SOLUTION FOUND
Time used: 0.0 secs
Memory used: 0.1 Mb (84145 bytes)
All the best,
Roberto
--
Prof. Roberto Bagnara
Applied Formal Methods Laboratory
Department of Mathematics, University of Parma, Italy
http://www.cs.unipr.it/~bagnara/
mailto:bagnara at cs.unipr.it
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