[Symphony] warm_solve getting stuck?

[Menal Guzelsoy]

Ross,

Could you send me the test file and let me know which version you are using?

Menal.

Menal Guzelsoy
1610 4620455



On Thu, May 6, 2010 at 12:22 AM, Ross Anderson <rpanderson at gmail.com> wrote:
> Hi all,
>
> I'm attempting a warm start on a large MIP. I'm having trouble
> creating a minimal example, so for now I'll keep this general and hope
> there's an easy fix.
> The original solution works fine. I call sym_solve(env); with options
> keep_warm_start=TRUE
> node_limit=8000
> do_reduced_cost_fixing=0
>
> and I get a solution.
> Then I reset some params
>
> sym_set_int_param(env, "do_reduced_cost_fixing", 0); //this one is
> repeated so that I don't receive SYMPHONY can not resolve for the obj
> coeff change when reduced cost fixing is on
> sym_set_int_param(env, "node_limit", -1);
>
> I reset some obj coeffs,
> sym_set_obj_coeff(env, 142, -1);
>
> and resolve
> sym_warm_solve(env);
>
> Screen output starts repeatedly saying
> done: 10639 left: 2 ub: -886.16 lb: -886.15 gap: 0.00 time: 820
> ....The time increments each line, but "done", "left", "ub", "lb", and
> "gap" don't change. This happens until I kill the process.
>
> If I instead begin the problem with the 142'th variable objective
> coefficient set to -1 (ie. without the warm start), everything works
> fine.
>
>
> Why is this getting stuck?
>
> Thank you
>
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