Constraint Implementation
-------------------------

You can find the files you need in /usr/local/eclipse/Tutorial/Exercises/2002

You need to use ECLiPSe 5.5 for these exercises:
/usr/local/eclipse/prerelease/bin/$ECLIPSEARCH/tkeclipse


1. Implement a constraint atmost/3 
	
	atmost(+N, +List, +V)

   which takes an integer N, an integer V and a list List
   containing integers or integer domain variables.

   Meaning: at most N elements of List have value V.

   Behaviour: Fail as soon as too many list elements are
   instantiated to value V.
   This requires only basic suspension facilities, no domain
   information needs to be taken into account.

   Improvement: Fail as soon as not enough variables with
   V in their domain are left over.

   Do not use the ic_global library...

   Tests are provided in the file
   	atmost.tst
   You can test your constraint by loading the library
       lib(test_util).
   and then calling
       test(atmost).


2. Implement a constraint offset/3

	offset(?X,+Const,?Y)

    which is declaratively like

	offset(X,Const,Y) :- Y #= X+Const.

  but maintains domain-arc-consistency (i.e. propagates
  "holes", while the above definition only maintains
  bounds-consistency).

  Use suspension built-ins and domain-access primitives
  from the ic_kernel module.
  Use not_unify/2 to test whether a value is outside
  a variable's domain.

   Tests are provided in the file
   	offset.tst
   You can test your constraint by loading the library
       lib(test_util).
   and then calling
       test(offset).