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Re: safety and external predicates

From: Gary Hallmark <gary.hallmark@oracle.com>
Date: Thu, 14 Aug 2008 12:12:35 -0700
Message-ID: <48A483A3.5030900@oracle.com>
To: Chris Welty <cawelty@gmail.com>
CC: Axel Polleres <axel.polleres@deri.org>, "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>

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 

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=
Received on Thursday, 14 August 2008 21:20:48 UTC

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