- From: Lee Feigenbaum <lee@thefigtrees.net>
- Date: 2009年4月27日 12:05:27 -0400
- To: Kingsley Idehen <kidehen@openlinksw.com>
- CC: Dan Brickley <danbri@danbri.org>, foaf-dev Friend of a <foaf-dev@lists.foaf-project.org>, Semantic Web <semantic-web@w3.org>
- Message-ID: <49F5D7C7.10209@thefigtrees.net>
[trimmed to: and cc: list a bit]
Kingsley Idehen wrote:
> Dan Brickley wrote:
>>
>> What % of "linked data" is truly free of bnodes?
>>
> Dan,
>
> I would safely say re. LOD Cloud somewhere north of 80% :-) And thats
> primary due to the content coming from PingTheSemanticWeb, otherwise I
> would say 90% and higher. The "Linked Data" meme has always encouraged
> URIs for everything.
This discussion is interesting to me. Kingsley's comment made me say
"huh, does dbpedia really only use URIs?"
so I ran:
select count(distinct ?s) where { ?s ?p ?o . filter(isblank(?s)) }
at http://dbpedia.org/sparql and received a result of 1330.
(i trired to compare with URIs by querying with isuri or with no filter,
but those queries timed out)
so there seem to be a few blank nodes scattered there, but not many. i
wanted to get an idea of what these blank nodes are used for, so i did:
select distinct ?p where { ?s ?p ?o . filter(isblank(?s)) }
http://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://www.w3.org/2002/07/owl#unionOf
http://www.w3.org/1999/02/22-rdf-syntax-ns#first
http://www.w3.org/1999/02/22-rdf-syntax-ns#rest
...which made it somewhat clear that blank nodes are used in dbpedia for
RDF lists and (?) anonymous classes.
Anyway.
Lee
Received on Monday, 27 April 2009 16:08:24 UTC