An adaptation of Constraint Handling Rules for Interactive and Intelligent Installations

Constraint Handling Rules, CHR, have proved to be effective for a large range of reasoning tasks, which makes it interesting in different sorts of interactive installations. Typically, such an installation involves a large number of cooperating software components that need to refer to a common knowledge. Using CHR’s constraint stores as a knowledge representation may be appealing from a theoretical point of view, but suffers from the inherent limitation of CHR, that a constraint store disappears immediately after a query has been evaluated. An extension to CHR is proposed, which allows different processes to reason over and maintain a common knowledge base represented as text files containing constraints. Constraints are automatically read from and written to the files before and after a query has been executed, which means that the intended style of programming deviates only very little from traditional CHR programming.