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Re: Open world issue (opening vs closing days) and SPARQL CONSTRUCT

From: Ivan Mikhailov <imikhailov@openlinksw.com>
Date: Wed, 21 May 2008 13:49:02 +0700
To: Pierre-Antoine Champin <swlists-040405@champin.net>
Cc: Bernard Vatant <bernard.vatant@mondeca.com>, Semantic Web <semantic-web@w3.org>
Message-Id: <1211352542.13676.123.camel@master.iv.dev.null>

Pierre-Antoine,

(:Tuesday :Sunday) is a good approach for non-SPARQL data retrieval,
say, for explicit graph traversal. Due to scalability reasons, SPARQL
has no features to deal with collections. Hence all what one can do with
SPARQL and (:Tuesday :Sunday) is to retrieve the head of the collection
and access it from application, making negation logic inside the
application. That's quite OK if the application is co-located with the
data source, otherwise one had to query for sequence items in sequence
via net with all related ping times.

Best Regards,

Ivan Mikhailov,
OpenLink Software.

On Wed, 2008-05-21 at 08:10 +0200, Pierre-Antoine Champin wrote:
> Bernard Vatant a écrit :
> > 
> > Hi all
> > 
> > We're currently fighting with knowledge extraction about opening/closing 
> > days for tourism facilities (hotels, restaurants, museums, campings ...).
> > Information can be found in terms of closing and/or opening days during 
> > a period, such as :
> > "Widget Museum is open in 2008, from March 1st to October 31st, closed 
> > on Sunday and Tuesday".
> > NLP can extract the following description (1)
> > 
> > :WidgetMuseum   :openingPeriod   _:p1
> > _:p1      :begins     2008-03-01
> > _:p1      :ends        2008-10-31
> > _:p1      :closingDay      :Tuesday
> > _:p1      :closingDay      :Sunday
> 
> May be I don't understand your problem well, but it seems to me that 
> there is another way of "closing" the world in this particulat context : 
> using a *functional* property :closingDays, and have its value be an 
> rdf:List collection, which in Turle/SPARQL is written :
> 
> :WidgetMuseum   :openingPeriod   _:p1
> _:p1      :begins       2008-03-01
> _:p1      :ends         2008-10-31
> _:p1      :closingDays  (:Tuesday :Sunday)
> 
> 
> Whether this structure is easy to query with SPARQL, I'm not sure... But 
> it seems to me that it makes your knowledge about opening and closing 
> days complete.
> 
>    pa
> 
> 
Received on Wednesday, 21 May 2008 06:53:13 GMT

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