[Developers] rdf auto-discovery and dbpedia

Mon Dec 1 19:56:17 UTC 2008

My apologies in advance for a somewhat tedious post. As a linked-data
enthusiast I was *really* pleased to notice just now that the public
interface for Freebase includes auto-discovery for the
application/rdf+turtle representations for a page:

For example if you view source on:

  http://www.freebase.com/view/en/space

You'll see this in the <head>:

  <link rel="alternate" type="application/turtle"
href="http://rdf.freebase.com/rdf/en.space">

Which sure enough, returns some Turtle for the concept of "Space".

Perhaps this is a question for the dbpedia discussion list, but I'm
curious why dbpedia links to what looks like the exact same resource
with a different URI. For example dbpedia asserts that:

  <http://dbpedia.org/resource/Space> owl:sameAs
<http://rdf.freebase.com/ns/guid.9202a8c04000641f8000000000036eca> .

And http://rdf.freebase.com/ns/guid.9202a8c04000641f8000000000036eca redirects:

  curl -I http://rdf.freebase.com/ns/guid.9202a8c04000641f8000000000036eca

  HTTP/1.0 302 FOUND
  Server: PasteWSGIServer/0.5 Python/2.4.4
  Date: Mon, 01 Dec 2008 13:52:24 GMT
  content-type: text/html; charset=utf-8
  location: http://rdf.freebase.com/rdf/guid/9202a8c04000641f8000000000036eca
  pragma: no-cache
  cache-control: no-cache
  Connection: close

But if you diff the turtle that comes back from this redirect with the
turtle that comes back from the URL we found via auto-discovery you
will discover that the descriptions are exactly the same (except for
the URIs being described)

  % curl -O http://rdf.freebase.com/rdf/guid/9202a8c04000641f8000000000036eca
  % curl -O http://rdf.freebase.com/rdf/en.space
  % diff 9202a8c04000641f8000000000036eca en.space
  7c7
  <  <http://rdf.freebase.com/ns/guid.9202a8c04000641f8000000000036eca>
a <http://rdf.freebase.com/ns/common.topic>,
  ---
  >  <http://rdf.freebase.com/ns/en.space> a
<http://rdf.freebase.com/ns/common.topic>,

So I'm left wondering, what is the URI for the concept of "Space" at
Freebase. Is it:

  http://rdf.freebase.com/ns/guid.9202a8c04000641f8000000000036eca

or:

  http://rdf.freebase.com/ns/en.space

I'm not trying to criticize, or be pedantic (because this is pretty
awesome stuff you guys are doing), but simple to understand better.

//Ed