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Newbie LOD Questions :)

From: Nathan <nathan@webr3.org>
Date: Wed, 28 Oct 2009 18:04:50 +0000
Message-ID: <4AE887C2.1060902@webr3.org>
To: public-lod@w3.org
Hi All,

Apologies if this is the wrong place to ask questions about linked data; 
however not sure where else to turn at the minute! and again as it's 
quite a long list.


worth noting the following link for most of the following questions:
http://sameas.org/text?uri=http%3A%2F%2Fdbpedia.org%2Fresource%2FLondon


1] Let's say I'm writing an article about London, England; which one of 
the many URI's do I reference that my data is "about"?

2] Would there be scope for a single globally unique identifier / URI to 
represent "London, England"? one which rather than holding information 
about London (like http://dbpedia.org/resource/London), essentially held 
a set of sameas items which everyone could use when publishing data 
"about" "London, England" (like the data at the sameas.org link above).

3] If sameAs indicates that two URI references contain information about 
the same thing; how do we assert that two URI's contain the same 
information about the same thing (ie identical data)?

3a] as [3], mirrors are common on the net, us1.domain us2.domain etc; 
each one containing the same information; as above how would one 
indicate that the data is the same? considering that ...
- the data is identical, no way to inject in a "sameas" in to the rdf
- one 3rd party may reference the uri 
http://us1.domain.com/something.rdf whilst another 3rd party references 
http://us2.domain.com/something.rdf
both are the same data, but no correlation between the two exists 
anywhere to say they are the same thing.
- it stands to reason that the ideal is a single endpoint and mirrors 
behind the scenes without any http 30* redirects ever being returned to 
the client, however this won't always be the case so what syntax can we 
use in this scenario?

[4] Are there any conventions or guidelines for combining data and 
resolving discrepancies? for instance to get all data about london one 
would theoretically have to combine all the data from the uri's 
referenced at (the sameas.org link aforementioned), but surely if you 
combined all data together then you'd get both duplicates and 
differences in the data.. which is fact etc.

[4a] Likewise with people - I have multiple social profiles all about 
"me" but surely in the near future multiple URI's will each represent 
#me; I think we can safely say that not all of these will be linked with 
sameas, and further still which one should X person use when referencing 
information about "me"?

[4b] Is there any method to mark which is the preferred source of 
information (and verify it)? at the minute it seems like it would be 
very simple to publish a vast amount of inaccurate data in triples and 
it appears the current mentality would be to take it for granted that 
the information IS fact.


DC vs ctag and FOAF

For RDFa we have ctag and maker; which to me seems very exact:
<span rel="ctag:means" resource="http://dbpedia.org/page/Washington"/>
<span rel="foaf:maker" resource="http://faviki.com/person/example#me"/>

but in dublin core we have the very loose
<span property="dc:subject">Washington</span>
<span property="dc:creator">Example</span>

I'm aware one can couple both dc and ctag/foaf in RDFa; but should we be 
replacing dc values wherever possible with the more precise ctag/foaf? 
(and indeed in our standard rdf data?)

A quick question about the usage of RDFa; previously I had always 
envisioned RDFa documents to contain a lot of inline rdf markup; I'm 
aware of the problems in picking up a term in the middle of a block of 
text and wrapping it in the appropriate notation; however my question is 
am I wrong in thinking this is the main use/advantage? in most cases 
where I've sen XHTML+RDFa (like uriburner etc) it's been more case of 
using RDFa to display human readable RDF; as opposed to human targeted 
article with rfda embedded in-place / in-line. Does anybody have any 
examples of a full RDFa demo site; not just with the normal dc/foaf and 
tags but fully enriched with detected semantic terms highlighted, linked 
and wrapped in rdfa, inline..?


And finally any info on creating a set/document which comprises of or 
includes / references items in other datasets? (I may really show my 
newbie-ness here) - what I mean is say I'm making an RDFa page about 
London, and in that I mention the population; I don't want to have the 
population in document or in the rdf, I do however want to link through 
to the triple which holds the population for london in dbpedia or a geo 
set and have that in my rdfa. So where I could have:
(spo)
london-population-7556900

I'd rather have:
london-population-{some link to dbpedia-owl:populationTotal value in 
dbpedia's rdf for london)

Thus I'm saying that london's population is {found here} and it'd be 
nice if it can also be pulled in and displayed through in an XHTML+RDFa 
document by possibly content="URI#dbpedia-owl:populationTotal" or suchlike.
Not sure if I explained that properly, perhaps just simply how do I 
reference a single triple rather than a full rdf set; or am I way of target?

Many Thanks in advance for any answers, comments etc & apologies again 
if it's the wrong place to ask!

Nathan
Received on Wednesday, 28 October 2009 21:15:02 UTC

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