Mon Sep 7 10:00:04 CEST 2009


The problem is the domain of the nodes.  Currently, they are limited
to values, and propagation performs assignment.  Let's clean this up
first by allowing subsets.

First: constraints need to perform propagation themselves.  This
should not be handled in the driver routine.

EDIT: equations and inequalities: equations useful for defining
intermediates on which the inequalities are specified.  When looking
from the point of individual get/set operations, the algorithm
performs directionalization of the equations + selects the appropriate
constraints to check.