EXPERT SYSTEMS BASED ON CONSTRAINTS
Roman Barták, Matematicko-Fyzikální Fakulta, EXPERTNê Systmy ZALOëEN, NA OMEZUJêCêCH PODMêNKçCH · 1999
Constraint hierarchies were introduced for describing over-constrained systems of constraints by specifying constraints with hierarchical strengths or preferences. Constraint hierarchies are widely used in areas like HCLP (Hierarchical Constraint Logic Programming) [9, 25] -- an extension of CLP (Constraint Logic Programming) [15] to include constraint hierarchies, CIP (Constraint Imperative Programming) [16] -- an integration of declarative constraint programming and imperative object-oriented programming, and graphical user interfaces construction [8]. The major advantage of constraint hierarchies is their declarative expression of preferences or strengths of constraints rather than encoding them in the procedural parts of the language. In a constraint hierarchy, the stronger a constraint is, the more it influences the solution of the hierarchy. Additionally, constraint hierarchy allows "relaxing" of constraints with the same strength via w