- From: Michael Kifer <kifer@cs.sunysb.edu>
- Date: Sun, 09 Apr 2006 18:13:32 -0400
- To: Dave Reynolds <der@hplb.hpl.hp.com>
- Cc: RIF WG <public-rif-wg@w3.org>
On 04 Apr 2006 Dave Reynolds <der@hplb.hpl.hp.com> wrote: > > This is an incomplete attempt to sketch out an example goal/csf/requirement > hierarchy to help me at least see the wood for the trees. > > This is not "right", just preliminary musings, so it can't go into the > Design Constraints page (violates the stated ground rules for that). Posted > in its current highly preliminary state in case it is a useful seed. Dave, This is a good high-level start. It needs to be refined and weeded out (i.e., there are problems :-) See below. > ** Goals > G1 Enable effective interchange of rules between existing rule systems > G2 Widespread adoption > G3 Foundation for a semantic web rule language > > ** Breakdown > > G1 Enable effective interchange of rules between existing rule systems > C1.1 Able to express the main features of relevant commercial rule systems > R1.1.1 Support for production rule languages > ... The devil is in the details. What is "effective" supposed to mean? If you intended that one set of production rules for Vendor X's engine will pass through RIF and emerge on the other end as a bunch of rules for Vendor Y's engine and the results will stay the same then keep dreaming. > C1.2 Interchanges can be meaning preserving > R1.2.1 RIF semantics is clear and precise > R1.2.2 RIF semantics is compatible with the rule languages to be > exchanged I hope that by RIF you mean a family of languages and you take the word semantics as plural (i.e., that there will be different semantics for different sublanguages of RIF). See my presentation on the DERI/RuleML position at F2F2. http://www.w3.org/2005/rules/wg/wiki/F2F2?action=AttachFile&do=get&target=DesignGoalsSessionDERI_RuleML_MichaelKSlides > C1.3 Cohesive, sufficiently few RIF dialects that there is useful > interchange I may be reading too much into your "sufficiently few" here, because later you talk about extensibility. But just in case, let me say this. One important requirement is that RIF should be *useful* and should not become irrelevant as technology marches on. This implies that RIF should be extensible, and this flies in the face of the "sufficiently few" requirement. I agree that we should start with few well-known paradigms, but the mechanism should be designed thoughtfully to enable extensibility. One way to do that is to propose a taxonomy of languages characterised by their salient semantic and syntactic features, as we proposed at the F2F. > G2 Widespread adoption > C2.1 Low cost of entry > R2.1.1 comprehensible and succinct specification documents > R2.1.2 (auxiliary) human readable syntax +1+1 I assume that here by "low cost of entry" you meant the cost for the users of RIF, not vendors. Your R2.1.* don't necessarily make life easy for vendors. > C2.2 Ease of "implementation" > R2.2.1 Sufficiently expressive that RLi -> RIFdialect is easy +1 > R2.2.2 Sufficiently inexpressive that RIFdialect -> RLj is easy Can't make sense out of it. If RIF is as expressive as every RLi then what does it mean to be "sufficiently inexpressive"? > R2.2.3 modest number of RIF dialects See above. > C2.3 Can be extended to handle interchange between languages not > explicitly considered by WG +1 > R2.3.1 Extensibility mechanism +1 > G3 Foundation for a semantic web rule language > C3.1 Webized > R3.1.1 predicates, instance objects etc designated by URIs > ... > > C3.2 Compatible with RDF > R3.2.1 RIF core must be able to accept RDF triples as data > R3.2.2 RIF core must be able to express RDF deduction rules RDF deduction rules? > ... > > C3.3 Compatible with OWL > R3.3.1 RIF Standard inference and OWL inference can be combined in a > well-defined fashion RIF "standard" inference? There can be no such thing given the diversity of the group. There are at least 3 streams in the RIFWG: pure FOL, logic programming, and production rules. Another member has joined recently, which brings in one more: reactive rules. In my F2F2 presentation mentioned above and in the RuleML 2005 paper http://www.debruijn.net/publications/msa-ruleml05.pdf a realistic hybrid architecture was proposed, which allows to combine the different paradigms in a loosely coupled fashion. There has also been work on combining FOL and LP approaches more tightly (the most recent is Rosati's DL+Log in KR2006). But this still leaves out production and reactive rules. It is more realistic to push for *interoperability* among RIF dialects and OWL/RDF rather than for "compatibility." In some important cases, compatibility is achievable (as shown by Rosati), but we should allow more flexibility (what we called "ad-hoc interoperability" in the DERI/RuleML presentation at F2F2). It is thus more realistic to build RIF around the roadmap that Harold presented at F2F2 http://www.w3.org/2005/rules/wg/wiki/F2F2?action=AttachFile&do=get&target=RoadmapSessionSlides http://lists.w3.org/Archives/Public/public-rif-wg/2006Feb/0255.html > ... > > C3.4 Compatible with SPARQL > R3.4.1 RIF Standard rules can query SPARQL data sources This is compatible with the hybrid architecture that I mentioned earlier. > R3.4.2 RIF Standard include SPARQL-compatible named graph support? This is also covered in http://www.debruijn.net/publications/msa-ruleml05.pdf and more. Regards, --michael
Received on Sunday, 9 April 2006 22:13:46 UTC