[Bonmin] turning off strong branching

[Stefan Vigerske]

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