Re: [Help-glpk] Branch and cut tree representation.

[Guerino Iacobucci]

Hi everyone,

i'm thinking to add into the struct 

struct IOSNPD

a new field named unique_id  into the header file glpios.h 

Another question, wher i can add the implementation of the function

int glp_ios_unique_id_node(glp_tree *T, int p);

Which this new field and new function i could give a name for each node and i can build the tree.

Is it a silly idea?

2010/2/24 Guerino Iacobucci <address@hidden>

Hi Mr. Makhorin,

i'm just thinking which i can comment this code line which call the function :

      ios_delete_node(tree, p);

in this point:

fath: /* the current subproblem has been fathomed */

      if (tree->parm->msg_lev >= GLP_MSG_DBG)

         xprintf("Node %d fathomed\n", p);

      /* freeze the current subproblem */

      ios_freeze_node(tree);

      /* and prune the corresponding branch of the tree */

      ios_delete_node(tree, p);    <------###########

      /* if a new integer feasible solution has just been found, other

         branches may become hopeless and therefore should be pruned */

      if (mip->mip_stat == GLP_FEAS) cleanup_the_tree(tree);

if i do that there are side effects or it is the right way?

Excuse me for my ignorance but i really don't understand by reading the reference how and which parameter 

i can give to the callback function, could you give an example?

Kind Regards,

IG

2010/2/24 Andrew Makhorin <address@hidden>

> Well, there is any way to obtain the entire list of nodes and build
> the tree?

Currently such a feature is not supported.

> Is possible to modify the B C api #39;s to obtain that list?

In principle, yes. You can trace each new node of the tree in the
the callback routine specifying it in the parameter list passed to
glp_intopt. For more details please see the glpk reference manual
included in the distribution.

Another way is to patch the glpk source code (see the routine
ios_driver in file src/glpios03.c). See also the BAK package
developed by Brady Hunsaker, which allows visualizing the search
tree for three mip solvers including glpk:
http://www.rosemaryroad.org/brady/software/index.html