[Help-glpk] Re: Re: branch-and-cut

[andre camatta]

My application was implemented in a similar way
(tspsol), but I don`t want that constraints are
deleted from the workspace when the subproblem has
been deleted. I wish that to each time that a
relaxation will be solved, I can  remove unnecessary
constraints, for example, the contraints with large
slack. My cutting planes are not very effective, the
LP's enlarge and it consumes more time, although the
number of visited nodes diminishes.

The number of rows increase in the course of the
algorithm (101 -> 307). The maximum number (limit) of
cuts added to each iteration in the application is 20.

Solving initial LP relaxation...
gm_scal: max / min = 5.100e+01
gm_scal: max / min = 7.106e+00
lpx_adv_basis: size of triangular part = 101
      0:   objval =   1.541000000e+03   infeas =  
1.000000000e+00 (0)
     99:   objval =   2.143138436e+03   infeas =  
1.200273190e-18 (0)
*   100:   objval =   2.143138436e+03   infeas =  
2.727157001e-15 (1)
*   131:   objval =   1.541000000e+03   infeas =  
2.316886053e-14 (0)
OPTIMAL SOLUTION FOUND
Integer optimization begins...
+   131:   intsol =   2.158000000e+03   (lev 0; lp
101, 385, 7070)
+  2800:   intsol =   2.022000000e+03   (lev 8; lp
163, 385, 9226)
+  3090:   intsol =   1.987000000e+03   (lev 10; lp
163, 385, 9226)
+ 10732:   intsol =   1.987000000e+03   (lev 14; lp
177, 385, 9798)
+ 15101:   intsol =   1.980000000e+03   (lev 18; lp
255, 385, 12770)
+ 22300:   intsol =   1.945000000e+03   (lev 15; lp
208, 385, 10846)
+ 49259:   intsol =   1.945000000e+03   (lev 40; lp
238, 385, 12068)
+ 70598:   intsol =   1.945000000e+03   (lev 63; lp
307, 385, 14502)
+ 72502:   intsol =   1.945000000e+03   (lev -1; lp 0,
0, 0)

Thanks,

André Camatta


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