  We identify a new and important global (or non-binary) constraint. This
constraint ensures that the values taken by two vectors of variables, when
viewed as multisets, are ordered. This constraint is useful for a number of
different applications including breaking symmetry and fuzzy constraint
satisfaction. We propose and implement an efficient linear time algorithm for
enforcing generalised arc consistency on such a multiset ordering constraint.
Experimental results on several problem domains show considerable promise.
