[Bonmin] turning off strong branching

[Pierre Bonami]

Hi Stefan,
Thanks, for pointing out this.
I think now it should be handled correctly.
Cheers,
Pierre
Stefan Vigerske wrote:
> Hi,
>
> I'm using Bonmin's B-BB algorithm and would like to turn off strong
> branching.
> However, when I set bonmin.variable_selection to most-fractional, then
> Cbc still says it does some strong branching:
>
> Cbc0032I Strong branching done 2 times (189 iterations), fathomed 1
> nodes and fixed 0 variables
>
>
> I also find the following code pieces confusing, esp. since they seem to
> be executed in this order, aren't they? Wouldn't that turn on
> strong-branching if varSelection == MOST_FRACTIONAL ?
>
> BonBabSetupBase.cpp:310
> if (varSelection == MOST_FRACTIONAL) {
>       intParam_[NumberStrong] = 0;
>       intParam_[MinReliability] = 0;
>
> options_->SetIntegerValue("bonmin.number_strong_branch",intParam_[BabSetupBase::NumberStrong],true,
> true);
> }
>
> BonBonminSetup.cpp:335
> if
> (!options_->GetIntegerValue("number_strong_branch",intParam_[BabSetupBase::NumberStrong],"bonmin."))
> {
>       intParam_[BabSetupBase::NumberStrong] = 1000;
>
> options_->SetIntegerValue("bonmin.number_strong_branch",intParam_[BabSetupBase::NumberStrong],
> true, true);
>     }
>
>
> Also MOST_FRACTIONAL is not handled by the switch at
> BonBonminSetup.cpp:346, leaving branchingMethod_ == NULL, I guess.
>
> However, when I set bonmin.variable_selection to random, then the
> message about how many strong branchings have been done disappears.
>
> Stefan
>
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