Simple predicate for instantiating a collection of GFD domain variables to elements of their domains. (Integers are also allowed in the collection; they are effectively ignored.) The variables are instantiated in the order in which they appear in the collection; the implementation is essentially:
	labeling(Vars) :-
		collection_to_list(Vars, List),
                gfd_update,
		( foreach(Var,List) do
		    indomain(Var,min)
		).
   Note that labeling performs the search in ECLiPSe, but it uses
   indomain/2 with min, which is optimised for use with Gecode, and a 
   gfd_update before the labeling starts to ensure that no recomputation
   will not be done for events before the labeling starts.