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For every pair of variables and
, we introduce a finite domain variable
to denote the relationship
that obtains between them.
and we freely identify
with
. In a solved form, every
must be determined.
In order to guarantee that a solved form is tree-shaped, for each pair of variables and
, we consider the 4 mutually exclusive possibilities. For each possible relation
we state that either
and the corresponding characteristic constraints
hold, or
and the constraints
characteristic of the negation hold.
Thus for each pair of variables and
, we stipulate that the following 4 Well-Formedness Clauses hold:
These clauses are all of the form . This denotes a disjunctive propagator and is explained in the next section.
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