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Re: Preprints from Journal of Web Semantics, v11 (2012)

From: Polleres, Axel <axel.polleres@siemens.com>
Date: Thu, 9 Feb 2012 00:02:21 +0100
To: Michael Brunnbauer <brunni@netestate.de>, "semantic-web@w3.org" <semantic-web@w3.org>
CC: Antoine Zimmermann <antoine.zimmermann@emse.fr>, Umberto Straccia <umberto.straccia@isti.cnr.it>, Nuno Lopes <nuno.lopes@deri.org>
Message-ID: <9DA51FFE5E84464082D7A089342DEEE80136CBB94DBB@ATVIES9917WMSX.ww300.siemens.net>
Hi Michael,

Thanks for the nice comment... Some answers inline below.
> -----Original Message-----
> From: Michael Brunnbauer [mailto:brunni@netestate.de]
> Sent: 08 February 2012 18:31
> To: semantic-web@w3.org
> Subject: Re: Preprints from Journal of Web Semantics, v11 (2012)
> hi all
> On Fri, Feb 03, 2012 at 02:35:57PM -0500, Tim Finin wrote:
> >  * A General Framework for Representing, Reasoning and Querying
> >    with Annotated Semantic Web Data, Antoine Zimmermann, Axel
> >    Polleres, Nuno Lopes and Umberto Straccia
> http://www.websemanticsjournal.org/index.php/ps/article/view/216
> I found this paper quite fascinating:
> The standard RDF semantics is replaced by a many valued logic with 
> truth values that build an algebraic semiring. The truth values 
> represent information about the minimum extent the information given 
> in the triple is considered to be true (e.G. temporal, provenance or 
> trust extent).
> The values do not have to be simple numbers but can be any data type 
> that builds a semiring - for example sets of time intervals or 
> propositional formulas built from atomic propositions about 
> provenance. The authors show how combinations of annotation domains 
> like temporal+fuzzytrust can be handled automatically.
> SPARQL is extented to support the annotation mechanism and quad 
> stores are suggested as storage where the context part of the quad 
> is a typed literal representing the annotation or truth value.
> Apart from the fact that this breaks most of the semantic web 
> standards and tools (how many quad stores do not support typed 
> literals as context ?), I like this.

First of all, this can be discussed, but in principle it should be 
possible to implemenmt our approach with either named graphs or quads.
Essentially giving each annotated triple a context identifier, and 
then You can express all the annotation values as property-values in 
triples over this context identifier.

> It would be interesting to know why the authors only use a subset of 
> RDFS and if there are obstacles to extending this to OWL full.

Our focus was on the framework for modeling context and inclusing it 
in the reasoning process, where we Concentrated on rule-based 
fragments that allow to implement this elegantly. It should be said 
that there are approaches doing similar things (only for the temporal 
domain, IIRC) ... cf. 

Boris Motik: Representing and Querying Validity Time in RDF and OWL: A Logic-Based Approach. International Semantic Web Conference (1) 2010: 550-565 

> I was thinking about how to achieve the same with named graphs but 
> this seems to get awkward with reasoning: Every named graph can only 
> have one annotation/truth value that is valid for all it's triples. 
> If you use a reasoning rule to deduce a triple out of n other 
> triples from several graphs, the annotation/truth value of the 
> deduced triple is computed from the value of the n other triples and 
> potentially new. As deduction rules are used recursively, you end up 
> with a plethora of annotation/truth values and each one requires a 
> separate named graph with deduced triples in it.

Well, yes and no... Only the maximum (in terms of the context lattice) annotation value counts, so the annotation value is always uniquely (and canonically representable) defined in our semantic framework defined in the paper..

> Are these dimensions (temporal, provenance or trust, etc.) so 
> important that we have to implement them as such (and reinvent 
> almost everything) or can we live with other solutions that probably 
> will be crippled in some way ?

Personally, I *do* think that certain contextual domains are crucial and the semantic Web will need a defined/agreed semantics for them. (validity) time, provenance are certainly the most prominent ones, IMHO.

> Regards,
> Michael Brunnbauer

Dr. Axel Polleres
Siemens AG Österreich
Corporate Technology Central Eastern Europe Research & Technologies CT T CEE
Tel.: +43 (0) 51707-36983
Fax: +43 (0) 51707-56682 mailto:axel.polleres@siemens.com
Received on Friday, 10 February 2012 08:05:41 UTC

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