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Re: Southampton Pub data as linked open data

From: Chris Bizer <chris@bizer.de>
Date: Wed, 30 Jul 2008 09:44:21 +0200
Message-ID: <002701c8f218$2eb5c360$c4e84d57@named4gc1asnuj>
To: <public-lod@w3.org>, <semantic-web@w3.org>
Cc: "Bijan Parsia" <bparsia@cs.man.ac.uk>, "John Goodwin" <John.Goodwin@ordnancesurvey.co.uk>, "Chris Wallace" <Chris.Wallace@uwe.ac.uk>, "Jens Lehmann" <lehmann@informatik.uni-leipzig.de>, "Richard Cyganiak" <richard@cyganiak.de>

Hi Bijan and Richard,

I think it would be helpful for this discussion to distinguish a bit between 
the different use cases of Semantic Web technologies.

Looking back at the developments over the last years, I think there are two 
general types of use cases:

1. Sophisticated, reasoning-focused applications which use an expressive 
ontology language and which require sound formal semantics and consistent 
ontologies in order to deliver their benefits to the user. In order to keep 
things consistent, these applications usually only work with data from a 
small set of data sources. In order to be able to apply sophisticated 
reasoning mechanisms, these applications usually only work with small 
datasets.

2. The general open Web use case where many information providers use 
Semantic Web technologies to publish and interlink structured data on the 
Web. Within this use case, the benefits for the user mainly come from the 
large amounts of Web-accessible data and the ability to discover related 
information from other data sources by following RDF links.

For each type of the use cases, there is usually a different set of 
technologies applied. OWL and classic heavy-weight reasoning for the first 
use case. HTTP, RDF, RDFS and light-weight smushing techniques for the 
second use case.

In the first use case, people think in terms of "ontologies", for instance a 
basic concept in OWL2 are ontologies. In the second use case, classes and 
properties are mixed from different vocabularies as people see fit and are 
related to each other by RDF links.

The second use case is inspired by the Web 2.0 movement and aims at 
extending the web with a
data commons into which *many* people publish data.

As it is not very likely that all these people will be logicians and 
understand (or are interested in) the formal semantics behind the things 
they do, people (including me) working on the second use case are often a 
bit critical about too tight formal semantics and extended public 
discussions about minor details that arise from some specs.

These discussions have been a mayor obstacle to deploying the Semantic Web 
over the last years as they drive away people away from using the 
technologies. I think that the normal Web developer will never bother going 
into the details of OWL (DL, 2 or whatever version). Fearing to do something 
wrong and state something that was not intended, common Web developers 
usually prefer not to touch these languages.

I'm personally convinced that we can do very cool things just with HTTP, RDF 
and RDFS for now and I see the current developments around Semantic Web 
browsers like Tabulator or Marbles, Semantic Web search engines like Sindice 
or Falcons and the growing number of people publishing Linked Data on the 
Web as clear indicators for this.

So why not being a bit more specific about the different use cases of the 
technologies and tell data publishers that it is OK just to use RDFS and 
that they do not have to care about the complicated details that arise from 
the different OWL specs.

Another idea along this line would be to rename OWL2 into Ontology 
Interchange Format (OIF). The Web rules language is already called Rules 
Interchange Format (RIF). Looking at the current OWL2 spec, I get the 
feeling that the working group designs a language for exchanging ontologies 
between knowledge based systems and that requirements from use case 2 do not 
play a very important role. Thus renaming the language could make the use 
case more clear and could be helpful for marketing the Semantic Web to Web 
developers that have understood the the benefits and limitations of 
microformats and now look for a better way to publish structured data on the 
Web.

Cheers

Chris


--
Chris Bizer
Freie Universitšt Berlin
+49 30 838 54057
chris@bizer.de
www.bizer.de
----- Original Message ----- 
From: "Jens Lehmann" <lehmann@informatik.uni-leipzig.de>
To: "Richard Cyganiak" <richard@cyganiak.de>
Cc: "Bijan Parsia" <bparsia@cs.man.ac.uk>; "John Goodwin" 
<John.Goodwin@ordnancesurvey.co.uk>; "Chris Wallace" 
<Chris.Wallace@uwe.ac.uk>; <public-lod@w3.org>; <semantic-web@w3.org>
Sent: Wednesday, July 30, 2008 7:47 AM
Subject: Re: Southampton Pub data as linked open data


>
>
> Hello,
>
> Richard Cyganiak schrieb:
>>
>> Bijan, Knud, Bernard, thanks for the clarification.
>>
>> I'm indeed surprised! Subclassing rdfs:label is okay in RDFS, and it is
>> okay in OWL Full, but it is not allowed in OWL DL.
>>
>> The RDF consumers I'm working on (RDF browsers and the Sindice engine)
>> don't care if you're in OWL DL or not, so I'm tempted to argue that it
>> doesn't matter much for RDF publishing on the Web. (IME, on the open
>> Web, trust and provenance are much larger issues than inference, and I
>> don't believe that the open Web will ever be OWL DL, so why bother.)
>
> Apart from the subject of this discussion, I find such general
> statements very dangerous. The fact that the tools you develop do not
> require, or make use of, OWL DL isn't really a strong argument. There
> are other people (like me) relying on reasoning, which is easier to
> accomplish in OWL DL. Clearly, it is important to publish data even if
> it does not conform to OWL DL, but that doesn't mean that we shouldn't
> bother to get it "right" (hopefully in OWL 2). Also note that it is not
> important for the whole open web to be in OWL DL, but only those bits of
> it you need for a particular task.
>
> Kind regards,
>
> Jens
>
>
> -- 
> Dipl. Inf. Jens Lehmann
> Department of Computer Science, University of Leipzig
> Homepage: http://www.jens-lehmann.org
> GPG Key: http://jens-lehmann.org/jens_lehmann.asc
> 
Received on Wednesday, 30 July 2008 07:45:48 UTC

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