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Re: [Help-glpk] reincarnation of tspsol

From: Andrew Makhorin
Subject: Re: [Help-glpk] reincarnation of tspsol
Date: Tue, 20 Oct 2015 07:44:05 +0300

>         > To avoid this, the rounding heuristic should be disabled.
>         > Unfortunately, there is no control parameter for this in
>         glp_iocp, so
>         > I'm attaching an awful hack to disable it from the tspsol
>         callback.
>         > This is only in case anyone gets an "Assertion failed: kk <=
>         n" error
>         > and wants to check if this is the reason, I would advise
>         against using
>         > it for any other reason.
>         >
>         Probably the fact of specifying the callback routine can be
>         used as a
>         flag to disable primal heuristics, because the callback
>         routine itself
>         is able to apply heuristics performing necessary feasibility
>         checks.
> I don't like the idea of disabling primal heuristics when a callback
> routine is used: This is the only case where I can see a problem,
> while I can think of many scenarios where the heuristics are desirable
> together with a callback.
> My preference is to have a flag in glp_iocp to enable the rounding
> heuristic (like fp_heur and ps_heur) that would be enabled by
> glp_init_iocp() but the user can then disable. Alternatively (or
> perhaps additionally), there could be a global flag to disable all
> heuristics.

Okay. I will add a flag to glp_iocp (say, row_gen) that explicitly
allows row generation. By default it is clear (no row generation is
allowed), and being set it disables all primal heuristics.

Andrew Makhorin

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