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Re: safety and external predicates

From: Michael Kifer <kifer@cs.sunysb.edu>
Date: Thu, 14 Aug 2008 17:30:44 -0400
To: Gary Hallmark <gary.hallmark@oracle.com>
Cc: Chris Welty <cawelty@gmail.com>, Axel Polleres <axel.polleres@deri.org>, "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>
Message-ID: <20080814173044.3b1964e2@kiferserv>

I agree. I don't quite see what are we (or anybody) is going to gain from
having this core dialect.

michael

On Thu, 14 Aug 2008 12:12:35 -0700
Gary Hallmark <gary.hallmark@oracle.com> wrote:

> 
> I think a better use of the group's resources would be to work on 
> dialects where there are real rules that could be interchanged.  For 
> example, members might help push PRD along, start work on FOL, or even a 
> SQL dialect.
> Core is whatever turns out to be in the intersection of the standard 
> dialects. 
> 
> Chris Welty wrote:
> >
> >
> > I still am not convinced that safeness is anything more than an 
> > academic requirement for CORE.  I would like to hear from someone who 
> > is a) interested in CORE and b) has some idea what an implementation 
> > is and c) has some idea what users of CORE would need, to let us know 
> > if these requirements matter:
> >
> > 1) Decidability: is is important that RIF-Core have decidable 
> > reasoning? That is, any compliant RIF-Core reasoner (implementation) 
> > will be guaranteed to terminate on any rule-set?
> >
> > 2) If decidability is a requirement, is tractability?  That is, any 
> > implementation will terminate in worst-case polynomial time (or better?)
> >
> > My general impression from talking to some potential RIF implementors 
> > is that they treat rule-bases like programs - if your programs don't 
> > work its your fault, go fix them.  However one important difference 
> > between rule/logic "programs" and procedural programs is the amount of 
> > control you have over the search strategy.  I think this is (a 
> > practical reason) why decidability is considered by some to be 
> > important for these languages and not for e.g. Java.
> >
> > -Chris
> >
> > Axel Polleres wrote:
> >>
> >> Two pointers here... the notion of strong safety in hex-programs 
> >> [1,2] and Topor's considerations on  safe database queries with 
> >> arithmetics [3] (cudos jos for the latter one)
> >>
> >>
> >> 1. R. Schindlauer. Answer-Set Programming for the Semantic Web. PhD 
> >> thesis, Vienna University of Technology, Dec. 2006.
> >> http://www.kr.tuwien.ac.at/staff/roman/papers/thesis.pdf
> >>
> >> 2.  Thomas Eiter, Giovambattista Ianni, Roman Schindlauer, and Hans 
> >> Tompits. Effective Integration of Declarative Rules with External 
> >> Evaluations for Semantic Web Reasoning. In York Sure and John 
> >> Domingue, editors, Proceedings of the 3rd European Conference on 
> >> Semantic Web (ESWC 2006), Budva, Montenegro, number 4011 in Lecture 
> >> Notes in Computer Science (LNCS), pages 273-287. Springer, June 2006.
> >> http://www.springerlink.com/content/f0x23wx142141v44/
> >>
> >> 3. R. Topor. Safe database queries with arithmetic relations (1991)
> >> Proc. 14th Australian Computer Science Conf 
> >> http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.48.4845
> >>
> >>
> >
> 
> 
Received on Thursday, 14 August 2008 21:32:31 GMT

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