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

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Mon, 19 May 2008 23:17:18 +0200
Message-ID: <4831EE5E.7080303@mondeca.com>
To: Semantic Web <semantic-web@w3.org>
Cc: Florence Amardeilh <florence.amardeilh@mondeca.com>, Steph <steph.weiser@gmail.com>, Philippe Laublet <Philippe.Laublet@paris4.sorbonne.fr>

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

In an open world, we have no way to know if this is a complete 
description, and can't infer that Widget Museum is open on Monday.

The other way round, if the information is given in terms of opening days,
"Widget Museum is open in 2008, from March 1st to October 31st, on 
Monday, Wednesday, Thursday, Friday and Saturday".
Which yields the description (2)

:WidgetMuseum   :openingPeriod   _:p2
_:p2      :begins     2008-03-01
_:p2      :ends        2008-10-31
_:p2      :openingDay      :Monday
_:p2      :openingDay      :Wednesday
_:p2      :openingDay      :Thursday
_:p2      :openingDay      :Friday
_:p2      :openingDay      :Saturday

... we can't infer that Widget Museum is closed on Tuesday and Sunday. 
IOW there is no way to identify logically _:p1 and _:p2 in an open world.

Supposing (1) is the standard target description required by the 
ontology used in the system, I thought possible to write, in our closed 
world, a SPARQL CONSTRUCT query which would yield (1) from (2).
But thinking twice, my hunch is now that it is impossible, because of 
the implicit open world assumption made by SPARQL.

Has someone already dealt with such issues? Any pointer welcome.

Thanks for your help

Bernard

-- 

*Bernard Vatant
*Knowledge Engineering
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*Mondeca**
*3, citÚ Nollez 75018 Paris France
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Mail:     bernard.vatant@mondeca.com <mailto:bernard.vatant@mondeca.com>
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Received on Monday, 19 May 2008 21:18:08 GMT

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