Re: [eclipse-clp-users] Multiple Value Ordering

From: Amine Marref <cyborgamine_at_...32...>
Date: Sat, 6 Feb 2010 20:52:21 +0000
Thanks Matthew and Helmut,

So far, 
1) I can use Matthew's trick (from previous response to this thread) which will only work with indomain_min, indomain_max.
2) Use search/6 twice as suggested by Helmut e.g. 
  bb_min(
            ( search(Vars1,0,input_order,indomain_min,complete,[]),Goal,bb_options{timeout:1},
              search(Vars2,0,input_order,indomain_max,complete,[]),Goal,bb_options{timeout:1}
            ).
I don't know what happens here at runtime though. Are all variables Vars1 assigned before all variables Vars2? If I have variables V1, V2, V3 that I want to assign in this order such that values of V1 are chosen indomain_min, values of V2 are chosen indomain_max, and values of V3 are chosen indomain_min, do I have to use 3 search/6 predicates? Or is the evaluation of the search/6 predicates parallel somehow, in which case, only two search/6 are needed?
3) Use a user-defined predicate e.g. search(Vars,0,input_order,my_value_ordering,complete,[]),Goal,bb_options{timeout:1}
my_value_ordering(X):-
  X is in Vars1 and indomain(X, min).
my_value_ordering(X):-

  X is in Vars2 and indomain(X, max).

My question, will (2) and (3) have same search space?

Also, will it be possible to show me a quick example on how the value assignment predicate "switches depending on some additional information you keep with each variable."

Many thanks.


> Date: Sat, 6 Feb 2010 20:18:28 +0000
> Subject: Re: [eclipse-clp-users] Multiple Value Ordering
> From: hsimonis@...70...
> To: cyborgamine@...32...
> CC: eclipse-clp-users_at_lists.sourceforge.net
> 
> Hi,
>  in one call of the search predicate you can only call one built-in
> strategy, but you can just call search twice, first for your Vars1 list,
> and then for your Vars2 list, and use different stategies in there.
> Alternative, you can define your own value assignment predicate which
> switches depending on some additional information you keep with each
> variable.
> 
> Helmut
> 
> >
> > Hello CLP people,
> >
> > Is it possible to use more than one value-ordering heuristic in search/6?
> >
> > In (dummy) example [1], I have two lists of variables: Vars1 and Vars2.
> > Currently, I search for Goal by labeling variables in both lists in
> > indomain_min fashion. Let's say that I know a priori that the optimal
> > solution is found faster if variables in Vars1 are labelled indomain_min
> > and variables in Vars2 are labelled indomain_max. I want to search for
> > Goal by using value choice "indomain_min over Vars1" and value choice
> > "indomain_max over Vars2". Is there any way to achieve this behaviour in
> > Eclipse?
> >
> > Amine.
> >
> > [1]
> > :-lib(ic).
> > :-lib(branch_and_bound).
> > :-lib(lists).
> >
> > solve(Goal):-
> >     Vars1 = [X1, X2, X3],
> >     Vars2 = [Y1, Y2, Y3],
> >     Vars1 #:: [1..10],
> >     Vars2 #:: [1..10],
> >     append(Vars1, Vars2, Vars),
> >     Goal #= Y1 + Y2 + Y3 - X1 - X2 - X3,
> >     bb_min(search(Vars,0,input_order,indomain_min,complete,[]),Goal,bb_options{timeout:1}).
> >
> >
> >
> >
> >
> >
> >
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> 
 		 	   		  
Received on Sat Feb 06 2010 - 20:52:29 CET

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