[Couenne] Disable NLP heuristic at root node

[Pietro Belotti]

Hi Manuel,

the heuristic called at the root node simply takes the NLP solution 
computed at the beginning of Couenne and returns it if feasible. It does 
not, by itself, run an NLP solver.

The call to the NLP solver at the beginning of Couenne is performed to 
obtain a feasible (though possibly fractional) point that is used by 
probing and other parts of Couenne. If you want to completely get rid of 
it, you may want to edit the source in 
Couenne/src/interfaces/BonCouenneInterface.cpp. Just comment out the call 
to initSolve() around line 145 and recompile. Given that Couenne relies on 
NLP solutions, this may actually hinder your chances of finding an optimal 
solution, so use this with caution. Note that you also need to exclude 
probing by adding the line

aggressive_fbbt no

to the option file.

I hope this helps. Regards,
Pietro

--
Pietro Belotti
Dept. of Mathematical Sciences
Clemson University
email: pbelott at clemson.edu
phone: 864-656-6765
web:   http://myweb.clemson.edu/~pbelott

On Wed, 23 May 2012, Manuel Ruiz wrote:

> Hi all,
> My question is about the local optimisation heuristic used in Couenne.  Althougt I put
> the line "local_optimization_heuristic no" in the couenne.opt file, the heuristic is
> still called at root node. Is it possible to disable it definitly ?
> 
> Regards
> 
> --
>   Manuel Ruiz