[gecode-users] mzn-gecode search strategy

[Tias Guns]

On Thu, 18 Apr 2013 09:36:13 +0200, Guido Tack <tack at gecode.org> wrote:

> Hi Tias,
>
> it's slightly complicated (and it has changed in Gecode 4).  The default  
> search is implemented in gecode/flatzinc/flatzinc.cpp in function  
> createBranchers, and the defaults in 4.0.0 are
>
>     branch(*this, iv_sol, INT_VAR_AFC_SIZE_MAX(0.99), INT_VAL_MIN());
>     branch(*this, bv_sol, INT_VAR_AFC_MAX(0.99), INT_VAL_MIN());
>     branch(*this, fv_sol, FLOAT_VAR_SIZE_MIN(), FLOAT_VAL_SPLIT_MIN());
>     branch(*this, sv_sol, SET_VAR_AFC_SIZE_MAX(0.99), SET_VAL_MIN_INC());
>
> where iv_sol are the variables mentioned in the output statement and not  
> mentioned in an explicit search annotation, and
>
>       branch(fzs,fzs.iv_aux,INT_VAR_AFC_SIZE_MAX(),INT_VAL_MIN());
>       branch(fzs,fzs.bv_aux,INT_VAR_AFC_MAX(),INT_VAL_MIN());
>       branch(fzs,fzs.sv_aux,SET_VAR_AFC_SIZE_MAX(),SET_VAL_MIN_INC());
>       branch(fzs,fzs.fv_aux,FLOAT_VAR_AFC_SIZE_MAX(),FLOAT_VAL_SPLIT_MIN());
>
> where iv_aux are variables introduced by mzn2fzn that are not  
> functionally defined.
>
> I'm planning to introduce annotations  
> default_{int,bool,set,float}_search that you can stick on the solve item  
> to change the default for the different variable types - would that be  
> useful?

Yes.

But since your asking, would there be a way to express the exact search  
strategy (on the *_sols) in minizinc itself, instead of introducing a new  
default_* annotation?

For example:
int_search(IntVars, size_afc_max(0.99), indomain_min, complete);

(I guess the only difference with what is available now is adding the  
0.99?)


Kind regards,
Tias

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