Filtering Algorithms for Tabular Constraints

Constraint satisfaction technology supports all constraint types, i.e. arbitrary relations can be expressed, theoretically. However, in practice constraint packages support only some constraints, namely arithmetical, logical, and special purpose global constraints. If a general relation constraint needs to be expressed, the user is forced to represent it as a system of supported constraints or to design a special filtering algorithm for it. In this paper we describe filtering algorithms for general binary constraint whose domain can be expressed as a table of compatible pairs of values. Such constraints may appear in practical applications where the final user (rather than the developer) specifies the constraint domain using a simple user interface, e.g., using a table.