- From: Francois Bry <bry@ifi.lmu.de>
- Date: Wed, 01 Feb 2006 08:58:37 +0100
- To: "Ginsberg, Allen" <AGINSBERG@imc.mitre.org>
- Cc: public-rif-wg@w3.org
Dear Allen, You wrote: >Hi Francois, > >In my opinion the RIF should definitely allow for expressing whatever >is necessary to enable automatic translation of rules across >rule-systems. By "translation" I mean an interchange that preserves at >least "operational equivalence" (which can be defined) if not logical >equivalence. Perhaps such translations can be done without semantic >information in the case of rule-systems within the same family >(meta-model), but I think it is highly unlikely that they can be done >across rule-systems in different families. > >At any rate, that was the point of the "Modest Proposal." We should >work out some simple concrete examples to see what is involved in this >enterprise. Then we will be better able to assess to what degree >expressing semantic information is required. > > I agree that RIF should have (1) a clear declarative semantics and (2) in addition support conveying *some* *limited* specifications of procedural semantics (eg backward chaining is intended because with forward chaining the considered rules would require to process all/too many nodes on the Web). I consider not realizable to specify a RIF "that preserves operational equivalence" between several rule languages. In my opinion, the choice we are facing can be expressed as "lingua franca" vs. "esperanto". Lingua franca is based on an abstract model that abstracts out many important aspects of languages thus making interchange between many possible at low efforts. Esperanto is a well designed full-fledged language that make it possible to translate from or to other languages while preserving "operational equivalence". The Esperanto approach has two drawbacks: its design is extremly expensive and its acceptance is extremely low, the reason being that human being - including computer scientists - like using special languages - including computer science languages - for building up, or maintain, sub-communities. Back to RIF: I beleive RIF should give rise to express: - logical formulas in a FOL style (preferably using a rich syntax) - intended use of the formulas (eg deduction rule, integrity constraints, ontologies) - intended negation (monotonic or non-monotonic) - intended declarative semantics (eg Well Founded or Stable Model or FOL) - intended truth valuations of all kinds (including discrete truth valuations such as eg true/false, true/unknown/false, known-tue/possibly-true/possibly-false/known-false as well as continous truth valuations such as [0..1] 0 meaining false, etc.) - schemas (in the acception of RDFS) ie what is also called sorts in automated reasoning and logic (ie classes and sub-class relationships and the like) - name (not procedural semantics!) of the rule engine the rules have been designed for. - maybe further "properties". Of course, RIF should make it possible that some of the above is not specified with a ruleset. Regards, -- Francois
Received on Wednesday, 1 February 2006 07:58:55 UTC