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

Dear Doerthe,


Thanks for keeping this ball rolling and I'm happy to say

+1


Kind regards,

Jos


Jos De Roo     | Agfa HealthCare
Data Scientist | HE/Clinical Analytics
http://josd.github.io/

Agfa HealthCare NV, Moutstraat 100, B-9000 Gent, Belgium
http://www.agfa.com/healthcare

________________________________
From: Doerthe Arndt <doerthe.arndt@ugent.be>
Sent: 22 November 2018 15:34:54
To: semantic-web@w3.org
Subject: Lack of a standard rules language Re: Toward easier RDF: a proposal

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<mailto:doerthe.arndt@ugent.be>