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

From: Peter Ansell <ansell.peter@gmail.com>
Date: Wed, 21 May 2008 16:28:27 +1000
Message-ID: <a1be7e0e0805202328l4e6a5a61k8730427d5bc662b7@mail.gmail.com>
To: "Semantic Web" <semantic-web@w3.org>

2008/5/21 Pierre-Antoine Champin <swlists-040405@champin.net>:
> 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.

RDF Collections, including List's are defined to be complete [1], so
that may be one way of getting around the open world assumption, but
how would you imply that a given day was valid and still not in the
closingDays List? Do you have to create another List for openingDays,
which would limit this ability to cases where you know everything?

[1] http://www.w3.org/TR/rdf-schema/#ch_collectionvocab

Received on Wednesday, 21 May 2008 06:29:02 UTC

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