Re: Converting RDF to JSON-LD : shared lists between graphs

On 25 July 2014 04:48, Pat Hayes <phayes@ihmc.us> wrote:
>
> On Jul 23, 2014, at 2:21 PM, David Booth <david@dbooth.org> wrote:
>
>> Hi Kingsley,
>>
>> On 07/23/2014 10:13 AM, Kingsley Idehen wrote:
>>> On 7/23/14 6:46 AM, Dan Brickley wrote:
>>>>> How so?  It seems to me that there is an inherent tension between
>>>>> being nice
>>>>> >to RDF consumers (by using URIs for things that other might want to
>>>>> refer
>>>>> >to, as AWWW recommends) and author convenience, which leads to bnode
>>>>> use.
>>>> Yes, that's a real tension, although bnodes are just one aspect. My
>>>> point was to question the "clearly" in  "the use of blank nodes
>>>> clearly violates the web architectural good practice that anything of
>>>> importance should be given a URI". Using bnodes is consistent with the
>>>> things the bnodes represent having URIs, so nothing is violated. The
>>>> reason btw we renamed them "bnodes" instead of the earlier (1997-2000
>>>> e.g.http://www.w3.org/2000/03/rdf-tracking/#rdfms-identity-anon-resources)
>>>>
>>>> phrase "anonymous nodes" was this point: the things are not anonymous
>>>> / nameless. Only particular descriptions of them.
>>>>
>>>
>>> +1
>>>
>>> Using pronouns (from natural language) to explain the nature of blank
>>> nodes helps a lot.
>>
>> Maybe, but pronouns are used *very* differently than blank nodes, so it really isn't an accurate comparison.  Normally when a pronoun is used, the corresponding noun is *also* used, so the reader can easily determine the intended noun.  ("When *Jack* got to the bank, *he* stopped.")  But that is not usually the case with blank nodes.  Usually if a blank node is used in an RDF document, no equivalent URI is given for that node.  But still, I can see how the analogy could help sometimes.
>
> The correct analogy is with indefinite pronouns like "someone" or "something". But many uses of blank nodes are in fact more like indefinite noun phrases, eg a bnode with an rdf:type link to http://dbpedia.org/ontology/tree is almost an exact rendering of the English phrase "a tree".
>
> BTW, recent work crawling the actual existing semantic web shows that about 40% of deployed RDF uses blank nodes. So apparently this "confusing" aspect of RDF is not confusing to a fair number of users. IMO all this noise about 'good' vs. 'bad' RDF is just that, noise. Actual users of RDF, as opposed to writers of technical blogs, seem to be able to handle RDF quite well.

Beyond those findings in "Everything You Always Wanted to Know About
Blank Nodes", we can add 6M+ internet domains publishing billions of
entity descriptions using schema.org, an RDF vocabulary. The vast
majority of this data shows up as bnodes in RDF. There are a few
tricks for data merging such as a http://schema.org/sameAs property
which points to indicative documents, e.g. see
https://support.google.com/webmasters/answer/4620133?hl=en rather than
trying to have the http-range-14 conversation with mainstream
webmasters.

The Linked Data thing began as TimBL expressing a concern that FOAF
data was needlessly bnodey - hence
http://www.w3.org/DesignIssues/LinkedData - and I think we're finally
settling into a kind of scruffy and pragmatic consensus that both
styles of graph have a role. High quality professionally published
Linked Data may lean more towards "well known URIs for all entities in
the graph", whereas mainstream markup will often use a bnode
formulation instead. Taking the Music Artists example from my google
link above, the JSON-LD schema.org triples tell you something like
this (subsetting for brevity):

A "MusicEvent" with "name" "B.B. King with Jonathon 'Boogie' Long" has
a "location" (which is a "Place" with "name" "Lupo's Heartbreak
Hotel"). That "Place" has an "address" that is a "PostalAddress",
which has such-and-so streetAddress, postalCode etc. The "MusicEvent"
has a "performer" that is a "MusicGroup". The "name" of that
"MusicGroup" is "Jonathon 'Boogie' Long". This same "MusicEvent" has
an "eventStatus" of "EventRescheduled", and a  "previousStartDate" of
"2013-09-30T19:30".

This seems to me (and to numerous publishers) to be reasonably
actionable and interpretable information, particularly since it is
also linked to well known Wikipedia and homepage URLs.

My preference is that we all stop trying to tell publishers how
exactly to manage their sites and databases, and deal with the fact
that they'll often have partial information without nice well known
URIs everywhere.

Dan

Received on Friday, 25 July 2014 16:30:50 UTC