W3C home > Mailing lists > Public > public-lod@w3.org > April 2011

Re: Linked Data, Blank Nodes and Graph Names

From: Melvin Carvalho <melvincarvalho@gmail.com>
Date: Mon, 11 Apr 2011 02:42:39 +0200
Message-ID: <BANLkTinrRmVQS_v61MZXZnssPhDwOFA=fg@mail.gmail.com>
To: nathan@webr3.org
Cc: Linked Data community <public-lod@w3.org>
On 7 April 2011 19:45, Nathan <nathan@webr3.org> wrote:
> Hi All,
>
> To cut a long story short, blank nodes are a bit of a PITA to work with,
> they make data management more complex, new comers don't "get" them (lest
> presented as anonymous objects), and they make graph operations much more
> complex than they need be, because although a graph is a set of triples, you
> can't (easily) do basic set operations on non-ground graphs, which
> ultimately filters down to making things such as graph diff, signing,
> equality testing, checking if one graph is a super/sub set of another very
> difficult. Safe to say then, on one side of things Linked Data / RDF would
> be a whole lot simpler without those blank nodes.
>
> It's probably worth asking then, in a Linked Data + RDF environment:
>
> - would you be happy to give up blank nodes?

*Disclaimer* I've not participated in an RDF WG or XG, but am a
hobbyist that tries to learn in their spare time, my knowledge if far
from complete.

That said, I'd be happy to give up blank nodes.

One less thing to worry about for the newcomer (my subjective POV),
and also it then means that I can maybe do things like c14n and
signing subgraphs more easily.

>
> - just the [] syntax?
>
> - do you always have a "name" for your graphs? (for instance when published
> on the web, the URL you GET, and when in a store, the ?G of the quad?
>
> I'm asking because there are multiple things that could be done:
>
> 1) change nothing
>
> 2) remove blank nodes from RDF
>
> 3) create a subset of RDF which doesn't have blank nodes and only deals with
> ground graphs
>
> 4) create a subset of RDF which does have a way of differentiating blank
> nodes from URI-References, where each blank node is named persistently as
> something like ( graph-name , _:b1 ), which would allow the subset to be
> effectively "ground" so that all the benefits of stable names and set
> operations are maintained for data management, but where also it can be
> converted (one way) to full RDF by removing those persistent names.
>
> Generally, this thread perhaps differs from others, by suggesting that
> rather than changing RDF, we could layer on a set of specs which cater for
> all linked data needs, and allow that linked data to be considered as full
> RDF (with existential) when needed.
>
> It appears to me, that if most people would be prepared to make the trade
> off of loosing the [ ] syntax and anonymous objects such that you always had
> a usable name for each thing, and were prepared to modify and upgrade
> tooling to be able to use this not-quite-rdf-but-rdf-compatible thing, then
> we could solve many real problems here, without changing RDF itself.
>
> That said, it's a trade-off, hence, do the benefits outweigh the cost for
> you?
>
> Best,
>
> Nathan
>
>
Received on Monday, 11 April 2011 00:43:06 UTC

This archive was generated by hypermail 2.3.1 : Sunday, 31 March 2013 14:24:32 UTC