#### Well-Formedness Clauses

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.

Denys Duchier
Version 1.2.0 (20010221)