##

Viewpoint

The term viewpoint goes back to Geelen [6] when
discussing permutation problems. Lee and Law [7] adopted
that concept and formally defined it.
A viewpoint is a pair (X,D), where X = {
*x*_{1},..., *x*_{n}}
is a set of variables, and D = {
*D*_{1},..., *D*_{n}} is a set
of associated domains for all *x*_{i} X.

Once having choosen the variables and their domains, the next
step is to search for a set of constraints such that the solutions
to the problem are determined by the solution to the constraints.
Obviously, the choice of the viewpoint affects the set of
constraints we need. So, different viewpoints for a problem
result in different sets of constraints and finally in completely
different models for a problem.

Andreas Rossberg
2006-08-28