I think Wendy Liu wrote: > [EMAIL PROTECTED] wrote: > > >I'm interested in > >rule right-hand-sides as well as left-hand sides; most of the XML rule > >languages are very oriented towards classical production systems in > >which RHSs can do nothing but assert/retract/modify; > > > Ernest, > > That is an interesting point. Can you give some examples or details of > what other types of RHS actions you have in mind?
Well, many rule engines (Jess included) have a complete procedural language you can use on rule RHSs. At the very least you need the ability to call a single function from the RHS, supplying arguments based on matched patterns from the LHS -- otherwise to do any real work you need "meta-programs," not describeable by the rule language itself, which watch for specific facts to appear and act on them. In Jess these meta-programs can be implemented directly in the rule language, but in a clasical production system they're part of the "glue code" that links the PS to the outside world. DAML, which is specifically based on the idea of representing knowledge so that inferences can be made without any outside meta-knowledge, is good and useful, but it does require these meta-programs as well to put the knowledge to use. In Mandarax, which is a Prolog-like backward chaining rule engine that is often used with RuleML, you program more or less procedurally by first querying the knowledge base to get a result set, then acting on it. Here you write the "meta-program" in Java, and the rules in RuleML. --------------------------------------------------------- Ernest Friedman-Hill Distributed Systems Research Phone: (925) 294-2154 Sandia National Labs FAX: (925) 294-2234 Org. 8920, MS 9012 [EMAIL PROTECTED] PO Box 969 http://herzberg.ca.sandia.gov Livermore, CA 94550 -------------------------------------------------------------------- To unsubscribe, send the words 'unsubscribe jess-users [EMAIL PROTECTED]' in the BODY of a message to [EMAIL PROTECTED], NOT to the list (use your own address!) List problems? Notify [EMAIL PROTECTED] --------------------------------------------------------------------
