JanM1

Jan Maluszynski
September 22, 2008 12:16 PM


> In my opinion the Working Draft on RIF-BLD of 30 July 2008
> is a  mature  document and I would be glad to see  a Candidate
>  Recommendation based on it. My interest on RIF-BLD is related
> to my work on integration of rules and ontologies under the
> well-founded semantics. 
> (see e.g. Wlodzimierz Drabent, Jan Maluszynski: 
> Well-Founded Semantics for Hybrid Rules. RR 2007:LNCS 4524,  1-15).
> 
> We are also working on rule languages
> where uncertainty is handled in the framework of Rough Sets.
> (see e.g. Jan Maluszynski, Andrzej Szalas, Aida Vitria:
>  A Four-Valued Logic for Rough Set-Like Approximate Reasoning. 
> T. Rough Sets 6: 176-190 (2007))
> 
> Some comments:
> 
> - Having more examples would be very helpful,
> 
> - The direct specification of RIF-BLD Semantics  (Section 3)  
> follows closely the Semantic Framework of the Working Draft on RIF-FLD.
> This is good,  but I would also expect to see  a  specialization of the
> general framework to the specific case of RIF-BLD.
> In particular, as RIF-BLD is claimed to correspond to the language
> of definite Horn rules, the minimal Herbrand model semantics, should
> perhaps be discussed. The minimal Herbrand model is   mentioned in
> Section 3.8 of the RIF-FLD Working Draft as  an intended semantic
> multi-structure of a RIF-BLD Sets of formulas,
> but is not mentioned at all in the RIF-BLD working draft. 
> Having clearly defined Herbrand models for RIF-BLD is
>  important for the extensions where rule bodies include
> negation-as-failure and for the approaches aiming on hybrid  integration
> of such rules and ontologies (including our work based on the well-founded
> semantics).
> 
> - The presentation syntax seems to be very useful. Having in addition 
>  a variant of it using standard mathematical notation for quantifiers
>  would be convenient in some cases, like teaching students with 
> the mathematical background. Also, I wonder if the  universal 
> quantification of rules must be explicit, in contrast to the standard
> implicit quantification used in logic programming.
> 
> Jan Maluszynski
> Department of Computer and Information Science 
> Linkoping University
> 581 83 Linkoping
> Sweden