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Re: OWL and LOD

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Tue, 12 May 2009 08:09:27 -0400
Message-ID: <4A0966F7.3020401@openlinksw.com>
To: John Goodwin <John.Goodwin@ordnancesurvey.co.uk>
CC: public-lod@w3.org, semantic-web@w3.org
John Goodwin wrote:
>
> Hi,
>
> I was just curious how many OWL sceptics we have in the LOD community? 
> Rightly or wrongly I get the impression there are a few?
>
> I've been integrating various LOD resource for a small demo at work 
> and have come to the realisation than a bit of relatively simple OWL 
> goes a long way in making the integration process more complete. Not 
> that is was a great surprise really, but you soon realise that 
> owl:sameAs only gets you so far. IMHO we really need to get OWL into 
> the LOD mix for linking vocabularies/ontologies as well as data at the 
> instance level. RDFS is not enough.
>
> A few simple examples… Say I want to integrate freebase and Dbpedia - 
> they both use there own ontologies/vocabularies/schema etc. Obviously 
> I can do owl:sameAs between common instances, but this doesn't fully 
> integrate the data in the way I would want. I was trying to do a 
> little demo around events, places and bands and soon found that 
> Dbpedia new about different bands from freebase. A simple query like 
> "find me information on punk rock bands playing in venues in 
> Southampton" was incomplete if I only used owl:sameAs. To get the full 
> information I needed to link the Dbpedia and freebase ontologies using:
>
> PunkRockGroups = music.musical_group and music.artist.genre value 
> en.punk_rock (Manchester OWL syntax).
>
> This way a query for things rdf:type PunkRockGroups also selects the 
> punk bands freebase knows about but Dbpedia doesn't…just doing 
> owl:sameAs would merely get information about punk bands that freebase 
> and Dbpedia share in common.
>
> Furthermore to link information about people born in Southampton from 
> freebase and Dbpedia I has to used:
>
> location.location.people_born_here owl:inverseOf dbpedia:birthplace
>
> Again a query dbpedia:birthplace Southampton now finds me people 
> freebase knows about as well as Dbpedia.
>
> Other simple examples of needing OWL with LOD are genealogy. I've 
> started to convert my family tree into RDF, e.g.:
>
> _http://www.johngoodwin.me.uk/family/I0265_
> _http://www.johngoodwin.me.uk/family/I0243_
>
> A bit of OWL e.g.:
>
> Parent = foaf:Person and isParentOf some foaf:Person
>
> isParentOf o isBrotherOf -> isUncleOf
>
> Uncle = foaf:Person and isUncleOf some foaf:Person
>
> Would save me writing long SPARQL queries for find instances of 
> Parent, Uncle etc.
>
> I know this isn't rocket science, but really hope a few simple 
> examples will start to convince OWL sceptics that OWL can really spice 
> up [1] LOD.
>
> Thoughts, comments, flamings :) welcome..
>
> John
>
> [1] as Kingley would say
>
>
>
> *Dr John Goodwin*
> *Research Scientist, Research, Ordnance Survey*
> C530, Romsey Road, SOUTHAMPTON, United Kingdom, SO16 4GU
> Phone: +44 (0) 23 8030 5756
> _www.ordnancesurvey.co.uk|_ <file://www.ordnancesurvey.co.uk%7C> 
> john.goodwin@ordnancesurvey.co.uk
> *Please consider your environmental responsibility before printing 
> this email*
>
John,

I frequently state the following: Linked Data is a bowl of spaghetti, 
OWL gives us the sauce, and inference rules the spicing. You need all 
three to make a really good meal :-)

Re. LOD and OWL I really don't know what the issues are per se. I do 
know from experience that interest in the likes of Yago, UMBEL, and 
OpenCyc remains strangely lukewarm. Even worse, I still see over 
generalized comments like: you can't reason over huge data sets even 
though we've offered inference rules based on Yago, UMBEL, and OpenCyc 
for over a year re. DBpedia [1] and more recently the larger Virtuoso 
instance which stores most of the LOD cloud datasets [2].

We handle, owl:sameAs, subclass, subproperty, equivalentClass, IFPs [3].

Note: re. <http://lod.openlinksw.com> when start your query from the 
"Search" tab, once you have an initial results page there is an 
"options" link for switching on inferences rules and owl:sameAs 
expansion, enable these options, andsubsequent queries will run with the 
Virtuoso's inference pragmas for SPARQL enabled. Also, simply click the 
SPARQL link to see the generated query.

Example:

DEFINE input:inference "http://dbpedia.org/resource/inference/rules/yago#"
DEFINE input:same-as "yes"
SELECT ?s1c as ?c1 count (distinct (?s1)) as ?c2
WHERE { ?s1 ?s1textp ?o1 . ?o1 bif:contains '(BILL AND CLINTON)' . ?s1 a 
?s1c .?s1 a <http://dbpedia.org/class/yago/Leader109623038> . }
GROUP BY ?s1c order by desc 2 limit 20 offset 0


Links:

1. http://dbpedia.org/sparql
2. http://lod.openlinksw.com/sparql
3. http://tr.im/l7HD -- a page that sheds more light on how we put 
inference rules to use re. <http://lod.openlinksw.com>
4. 
http://www.mail-archive.com/dbpedia-discussion@lists.sourceforge.net/msg00263.html 
--Yago examples from the past re. DBpedia inference rules (which are 
always in place)
6. http://www.mail-archive.com/public-lod@w3.org/msg00870.html -- UMBEL 
examples variant of what exists for Yago
7. 
http://osdir.com/ml/web.semantic.dbpedia.general/2008-05/msg00053.html 
-- DBpedia subproperties examples using Yago


-- 


Regards,

Kingsley Idehen	      Weblog: http://www.openlinksw.com/blog/~kidehen
President & CEO 
OpenLink Software     Web: http://www.openlinksw.com
Received on Tuesday, 12 May 2009 12:10:17 GMT

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