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Re: Lack of a standard rules language Re: Toward easier RDF: a proposal

From: Paul Tyson <phtyson@sbcglobal.net>
Date: Sun, 25 Nov 2018 12:34:30 -0600
Message-ID: <1543170870.1931.16.camel@sbcglobal.net>
To: Nathan Rixham <nathan@webr3.org>
Cc: Doerthe Arndt <doerthe.arndt@ugent.be>, W3C Semantic Web IG <semantic-web@w3.org>
On Thu, 2018-11-22 at 14:47 +0000, Nathan Rixham wrote:
> Yes, N3 immediately addresses multiple points from the opening thread.
> 
> 
> It's a great starting (and ending?) point, to this 
> 

The original defect report ("Lack of a standard rules language") is
wrong. RIF has been in the SemWeb stack for a long time. It has of
course been largely ignored while practitioners invent special-case
solutions.

RIF is directly compatible with XML, RDF, and OWL, which means you have
a lot of basic tooling to process it. It covers practically all rule
styles anyone would want, and includes a standard extension mechanism.

My only complaint about RIF is that, due to timing of the working
groups, it is not fully interoperable with SPARQL. Also for the same
reason, there is some disconnect between RIF datatypes and built-ins,
and the XSD datatypes and xpath functions. It's been quite a while since
I worked in this area so I don't recall the details.

That should be the starting point on this topic: re-open a working group
on RIF to make it capable of expressing SPARQL constructs, and resolve
the datatype and built-in discrepancies with other W3C specs.

Of course additional tooling, documentation, and advocacy for RIF
wouldn't hurt. But first drop the myth about "no standard rule
language".

Regards,
--Paul

> On Thu, 22 Nov 2018, 14:40 Doerthe Arndt <doerthe.arndt@ugent.be
> wrote:
> 
>         Dear all, 
>         reading the below:
>         
>         
>         > 
>         > 8. Lack of a standard rules language.  This is a big one. 
>         > Inference is fundamental to the value proposition of RDF, 
>         > and almost every application needs to perform some kind 
>         > of application-specific inference.  ("Inference" is used 
>         > broadly herein to mean any rule or procedure that produces
>         > new 
>         > assertions from existing assertions -- not just
>         > conventional 
>         > inference engines or rules languages.)  But paradoxically, 
>         > we still do not have a *standard* RDF rules language. 
>         > (See also Sean Palmer's apt observations about N3
>         > rules.[14]) We want to move forward the standardisation of
>         > N3 since I think that it is really worth it:
>         
>         I think this is a good opportunity to get back to N3 Logic. We
>         have worked with N3 for years now and there are several
>         reasons why I believe that it should be standardized:
>         
>         
>               * Syntax: 
>                 
>                 For someone knowing turtle, writing N3 rules is easy
>                 since N3 seamlessly extends the rdf's turtle syntax
>                 without having to fall back on debatable constructs
>                 like reification. 
>                 Example: 
>                 For a triple :s :p :o. a rule  {?x :p :o} =>
>                 {?x :pp :oo}. would lead to :s :pp :oo.
>                 
>                 For reification, N3 also provides a solution in
>                 general which is very close to the recent proposal of
>                 RDF* and could be aligned with it. 
>                 Example: :s :says {:s :p :o}.
>               * Practice: 
>                 
>                 There are already existing reasoners for N3 Logic Like
>                 Cwm (https://www.w3.org/2000/10/swap/doc/cwm.html) and
>                 EYE (http://eulersharp.sourceforge.net/). The latter
>                 developed in industry which can make us at least
>                 confident that N3 is able to cover "real" use cases.  
>                 
>                 We used N3 in many practical use cases and had
>                 positive experiences (for example
>                 https://de.slideshare.net/ruleml2012/ruleml-2015-ontology-reasoning-using-rules-in-an-ehealth-context and https://biblio.ugent.be/publication/8540876).
>         
>         We already did some first steps towards the standardization by
>         defining a model theory and identifying current problems:
>         
>               * A recent talk about this topic at the RuleML Webinar
>                 (https://wiki.ruleml.org/index.php/RuleML_Webinar) can
>                 be accessed here:
>                 https://github.com/RuleML/ruleml-website/blob/master/talks/DoertheArndt-SemN3Impl2ExplQuant-RuleMLWebinar-2018-09-28.pdf 
>               * Earlier work was presented at RuleML 2015 (Slides:
>                 https://de.slideshare.net/ruleml2012/ruleml-2015-semantics-of-notation3-logic-a-solution-for-implicit-quantification, Paper: https://link.springer.com/chapter/10.1007/978-3-319-21542-6_9)
>               * We furthermore hope to soon publish a journal paper
>                 about this topic which is currently under review.
>         
>         Call to action: who would support and/or join a W3C community
>         group around an N3 rule language?
>         
>         
>         Regards,
>         
>         Doerthe
>         
>         
>         P.S.: To also get back to the rest of the ongoing discussion:
>         N3 supports blank nodes and literals in all positions and
>         treats lists as "first class citizens" (in practice that means
>         that there are no blank nodes involved when expressing lists).
>         
>         
>         -- 
>         Dörthe Arndt
>         Researcher Semantic Web
>         imec - Ghent University - IDLab | Faculty of Engineering and Architecture | Department of Electronics and Information Systems
>         Technologiepark-Zwijnaarde 19, 9052 Ghent, Belgium
>         t: +32 9 331 49 59 | e: doerthe.arndt@ugent.be 
Received on Sunday, 25 November 2018 18:35:03 UTC

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