[SCIP] set/vbc/dispsols

[Jakob Witzig]

Hi Uwe,

I had a look into the code and it seems that the vbc-format does not 
support information about the new incumbent solution. If you use bak 
instead of vbc, SCIP will print a line like:

integer {nodenumber} {parentnumber} {boundtype} {newobj}

The "frac" column shows the number of fractional variables in the LP 
solution. If all integer variables have an integral solution value in 
the LP solution a "-" is printed.

Cheers,
Jakob

Am 16.12.2016 um 12:02 schrieb Gotzes, Uwe Dr.:
> Hi,
>
> I have a very simple problem and tried to tell scip to apply plain lp-based branch and bound to it.
>
> I have set vbc/dispsols = TRUE to visualize the nodes where solutions are found.
>
> This option results in the two lines 00:00:00.00 P 6 14 and 00:00:00.00 P 5 14 in the vbc-file. (P int int Number of the node, number of the nodes colour.)
>
> I have two questions:
> 1. Is it possible to figure out the value of the solution found in the respective node from the vbc-file?
> 2. What is the meaning of the minus sign in the "frac"-column of node 2?
>
>
> Scip output is:
>
>  time | node  | left  |LP iter|LP it/n| mem |mdpt |frac |vars |cons |cols |rows |cuts |confs|strbr|  dualbound   | primalbound  |  gap
>   0.0s|     1 |     0 |     0 |     - | 166k|   0 |   - |   2 |   3 |   2 |   0 |   0 |   0 |   0 |      --      |      --      |    Inf
> (node 1) LP relaxation is unbounded (LP 0)
>   0.0s|     1 |     0 |     2 |     - | 167k|   0 |   - |   2 |   3 |   2 |   2 |   2 |   0 |   0 |      --      |      --      |    Inf
> (node 1) LP relaxation is unbounded (LP 1)
>   0.0s|     1 |     0 |     3 |     - | 168k|   0 |   1 |   2 |   3 |   2 |   2 |   3 |   0 |   0 |8.428571e+000 |      --      |    Inf
>   0.0s|     1 |     2 |     3 |     - | 168k|   0 |   1 |   2 |   3 |   2 |   2 |   3 |   0 |   0 |8.428571e+000 |      --      |    Inf
>   0.0s|     2 |     1 |     3 |   0.0 | 169k|   1 |   - |   2 |   3 |   2 |   2 |   3 |   0 |   0 |8.000000e+000 |      --      |    Inf
>   0.0s|     3 |     2 |     5 |   1.0 | 169k|   1 |   1 |   2 |   3 |   2 |   2 |   3 |   0 |   0 |7.500000e+000 |      --      |    Inf
>   0.0s|     4 |     3 |     6 |   1.0 | 170k|   2 |   1 |   2 |   3 |   2 |   2 |   3 |   0 |   0 |7.000000e+000 |      --      |    Inf
> * 0.0s|     5 |     2 |     7 |   1.0 | 170k|   3 |   - |   2 |   3 |   2 |   2 |   3 |   0 |   0 |7.000000e+000 |4.000000e+000 |  75.00%
> * 0.0s|     6 |     0 |     8 |   1.0 | 170k|   3 |   - |   2 |   3 |   2 |   2 |   3 |   0 |   0 |7.000000e+000 |7.000000e+000 |   0.00%
>
> The content of the generated vbc-file:
>
> #TYPE: COMPLETE TREE
> #TIME: SET
> #BOUNDS: SET
> #INFORMATION: STANDARD
> #NODE_NUMBER: NONE
> 00:00:00.00 N 0 1 3
> 00:00:00.00 I 1 \inode:\t1\idepth:\t0\nvar:\t-\nbound:\t-100000000000000000000.000000
> 00:00:00.00 P 1 11
> 00:00:00.00 N 1 2 3
> 00:00:00.00 I 2 \inode:\t2\idepth:\t1\nvar:\t-\nbound:\t-8.428571
> 00:00:00.00 I 2 \inode:\t2\idepth:\t1\nvar:\tt_x1 [-0,1e+020] <= 2.000000\nbound:\t-8.000000
> 00:00:00.00 N 1 3 3
> 00:00:00.00 I 3 \inode:\t3\idepth:\t1\nvar:\t-\nbound:\t-8.428571
> 00:00:00.00 I 3 \inode:\t3\idepth:\t1\nvar:\tt_x1 [-0,1e+020] >= 3.000000\nbound:\t-8.428571
> 00:00:00.00 I 1 \inode:\t1\idepth:\t0\nvar:\t-\nbound:\t-8.428571\nnr:\t1
> 00:00:00.00 P 1 2
> 00:00:00.00 I 3 \inode:\t3\idepth:\t1\nvar:\tt_x1 [3,1e+020] >= 3.000000\nbound:\t100000000000000000000.000000\nnr:\t2
> 00:00:00.00 P 3 2
> 00:00:00.00 I 3 \inode:\t3\idepth:\t1\nvar:\tt_x1 [3,1e+020] >= 3.000000\nbound:\t100000000000000000000.000000\nnr:\t2
> 00:00:00.00 P 3 4
> 00:00:00.00 N 2 4 3
> 00:00:00.00 I 4 \inode:\t4\idepth:\t2\nvar:\t-\nbound:\t-7.500000
> 00:00:00.00 I 4 \inode:\t4\idepth:\t2\nvar:\tt_x2 [-0,3] <= 0.000000\nbound:\t-7.500000
> 00:00:00.00 N 2 5 3
> 00:00:00.00 I 5 \inode:\t5\idepth:\t2\nvar:\t-\nbound:\t-7.500000
> 00:00:00.00 I 5 \inode:\t5\idepth:\t2\nvar:\tt_x2 [-0,3] >= 1.000000\nbound:\t-7.000000
> 00:00:00.00 I 2 \inode:\t2\idepth:\t1\nvar:\tt_x1 [-0,2] <= 2.000000\nbound:\t-7.500000\nnr:\t3
> 00:00:00.00 P 2 2
> 00:00:00.00 N 4 6 3
> 00:00:00.00 I 6 \inode:\t6\idepth:\t3\nvar:\t-\nbound:\t-6.000000
> 00:00:00.00 I 6 \inode:\t6\idepth:\t3\nvar:\tt_x1 [-0,2] <= 1.000000\nbound:\t-4.000000
> 00:00:00.00 N 4 7 3
> 00:00:00.00 I 7 \inode:\t7\idepth:\t3\nvar:\t-\nbound:\t-6.000000
> 00:00:00.00 I 7 \inode:\t7\idepth:\t3\nvar:\tt_x1 [-0,2] >= 2.000000\nbound:\t-6.000000
> 00:00:00.00 I 4 \inode:\t4\idepth:\t2\nvar:\tt_x2 [-0,0] <= 0.000000\nbound:\t-6.000000\nnr:\t4
> 00:00:00.00 P 4 2
> 00:00:00.00 I 6 \inode:\t6\idepth:\t3\nvar:\tt_x1 [-0,1] <= 1.000000\nbound:\t-4.000000\nnr:\t5
> 00:00:00.00 P 6 2
> 00:00:00.00 P 6 14
> 00:00:00.00 U -4.000000
> 00:00:00.00 I 5 \inode:\t5\idepth:\t2\nvar:\tt_x2 [1,3] >= 1.000000\nbound:\t-7.000000\nnr:\t6
> 00:00:00.00 P 5 2
> 00:00:00.00 P 5 14
> 00:00:00.00 I 7 \inode:\t7\idepth:\t3\nvar:\tt_x1 [-0,2] >= 2.000000\nbound:\t-6.000000\nnr:\t6
> 00:00:00.00 P 7 4
> 00:00:00.00 U -7.000000
>
> Thanks,
> Uwe
>
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-- 
Jakob Witzig

Zuse Institute Berlin (ZIB)

Division Mathematical Optimization and Scientific Information
Research Group Mathematical Optimization Methods

Takustrasse 7
14195 Berlin

Tel. : +49 (0)30 84185-416
Fax  : +49 (0)30 84185-269
email: witzig at zib.de