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How to query for Country Specific Data

From: <richard.hancock@3kbo.com>
Date: Sun, 24 May 2009 02:19:31 -0500 (CDT)
Message-ID: <45068.203.97.223.64.1243149571.squirrel@www.3kbo.com>
To: public-lod@w3.org
Hi all,

I am wondering what are the best queries to run against the various LOD
datasets in order to get an idea of what Linked Data is currently
available for a specific country, e.g. New Zealand.

My plan was to start with Dbpedia and move out from there but so far my
Dbpedia queries so far haven't yielded the results I was hoping for.

My initial reasoning was that I could use the Dbpedia country URI ( i.e. 
<http://dbpedia.org/resource/New_Zealand> ) as the beginning point for my
search and get a list of properties relating things to New Zealand using

SELECT DISTINCT ?p
FROM NAMED <http://dbpedia.org>
WHERE {
?s ?p <http://dbpedia.org/resource/New_Zealand> .
}

and a list of New Zealand properties using

SELECT DISTINCT ?p
FROM NAMED <http://dbpedia.org>
WHERE {
<http://dbpedia.org/resource/New_Zealand> ?p ?o  .
}

The first thing I looked for were properties that would let me find towns
and cities in New Zealand.

When I couldn't find obvious properties relating New Zealand towns and
cities to New Zealand I tried taking the URI of a specific city,
Wellington to see what properties linked it to New Zealand.

The query below shows that no property linked Wellington to New Zealand.

SELECT *
FROM NAMED <http://dbpedia.org>
WHERE {
 <http://dbpedia.org/resource/Wellington> ?p
<http://dbpedia.org/resource/New_Zealand> .
}

gives no results.

Going the other way showed that Wellington was the capital of New Zealand
but I was also expecting to see another property indicating that
Wellington was a city of New Zealand. I had hoped to find the second
property so that I could use it to find all other cities and towns within
New Zealand.

SELECT *
FROM NAMED <http://dbpedia.org>
WHERE {
 <http://dbpedia.org/resource/New_Zealand> ?p
<http://dbpedia.org/resource/Wellington>.
}

indicates that New_Zealand has a capital via
<http://dbpedia.org/property/capital> of Wellington

The best indication that Wellington is located in New Zealand was found
using the location property.

SELECT *
FROM NAMED <http://dbpedia.org>
WHERE {
<http://dbpedia.org/resource/Wellington>
<http://dbpedia.org/property/location> ?o .
}

gives the literal "Wellington, New Zealand"@en.

A scenario similar to the one between Wellington and New Zealand exists
between Berlin and Germany but here the literal value of the location
property proves less useful

SELECT ?location
FROM NAMED <http://dbpedia.org>
WHERE {
<http://dbpedia.org/resource/Berlin>
<http://dbpedia.org/property/location> ?location .
}

gives the literal "Berlin"@en

At this point I thought it was time to ask for help.

For the current Linked Data sets what is the best approach to take when
seeking to find what information has already been published for a specific
country ?

Depending on what you are looking for are some datasets better starting
points than others? E.g. for finding the towns and cities is geonames
(http://sws.geonames.org/) ,CIA Factbook or some other dataset, a better
starting point?

For Dbpedia are there plans to migrate properties like location
<http://dbpedia.org/property/location> which currently use literals to use
URIs instead?

Cheers,

Richard Hancock
Received on Sunday, 24 May 2009 07:20:13 UTC

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