W3C home > Mailing lists > Public > semantic-web@w3.org > August 2012

Re: Why do we name nodes and not edges?

From: adasal <adam.saltiel@gmail.com>
Date: Wed, 1 Aug 2012 16:38:03 +0100
Message-ID: <CANJ1O4ohY1W=o=3WM-S+fGm+UheHBWzKKUspAgcowc+z_4EegA@mail.gmail.com>
To: Stephen Williams <sdw@lig.net>
Cc: semantic-web@w3.org
Stephen Williams wrote:-


> Please let me know if you are interested in exploring the idea and helping
> to implement this in one way or another.  In particular, I need (and may
> create) a SQLite-like licensed library (Apache 2, MIT, or a commercial
> license with few restrictions, etc.) that can be used widely without
> restriction.  Which may of course just be a layering on SQLite initially,
> although that likely won't be efficient and scalable enough for my purposes.


I am curious,  would the following graph data base help? Or Neo4J?

Or, at least a good place to start? Notice the restriction on size using
Berkley backend, but no necessary tie to this, I think.

Thanks to all for the discusion, very helpful.
I am going to use it to help me explain the relationship between graphs and
topology in a unrelated, non-computer, domain.

Adam

+++++++++++++++++++++++++++++++++++++++++++++

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(news, hypergraphdb published on June 11, 2012)

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Graph-oriented storage.
N-ary, higher order relationships (edges) between graph nodes.
Graph traversals and relational-style queries.
Customizable indexing.
Customizable storage management.
Extensible, dynamic DB schema through custom typing.
Out of the box Java OO database.
Fully transactional and multi-threaded, MVCC/STM.
P2P framework for data distribution.

In addition, the project includes several practical domain specific
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On 30 July 2012 18:47, Stephen Williams <sdw@lig.net> wrote:

>  On 7/29/12 6:09 AM, Nathan wrote:
>
> David Booth wrote:
>
> Another approach (instead of reification, which I personally hate), is
> to use named graphs.  Named graph have to be used differently, but can
> often solve the same use case.
>
> For RDF stores that store everything as quads anyway, my guess is that
> even if you have only one named graph per triple it would likely involve
> less overhead than reification, but perhaps one or more of the
> developers of such stores can comment on that more authoritatively.
>
>
> As I understand it, Melvin is looking for a well defined function that
> would allow one to canonicalize a triple (edge) in to a unique URI. Such
> that f(subject, predicate, object) = edge:123234234 .
>
> Reification allows you to name a triple, but it's not in a canonical form
> with a unique name per triple.
>
>
> At at W3C plenary at MIT several years ago, I asked TBL why triples and
> not quads.  To which he replied, they are quads: the forth element is just
> usually implied (or something close to that).
>
> I've long thought that we need unique identification of each triple and to
> be able to uniquely group arbitrary subsets of statements in a "triple
> store" so that the subset can be referred to easily.  My solution is to
> represent "triples" as pents: triple+ID+context, where context is very
> general purpose and semi-automatically maintained.  Going further, I am
> mostly convinced that it should be a "hex" with two kinds of context:
> provenance / certainty (time stamps, source, several types of trust) and
> statement subset association.  (There is one further level needed in my
> system, but I won't go into that here yet.)  I need to implement this soon
> and have a number of ideas about how this should work to be efficient and
> scalable.
>
> Please let me know if you are interested in exploring the idea and helping
> to implement this in one way or another.  In particular, I need (and may
> create) a SQLite-like licensed library (Apache 2, MIT, or a commercial
> license with few restrictions, etc.) that can be used widely without
> restriction.  Which may of course just be a layering on SQLite initially,
> although that likely won't be efficient and scalable enough for my purposes.
>
> With current standards, this would be externalized as reified RDF if
> "everything" were exported, or simple triples if the metadata is elided.
> Probably a new twist on external representation would be useful.
> Additionally, based on my work related to W3C EXI and my own binary XML
> work, I have had a number of ideas related to a binary RDF/pent/hex/ntuple
> interchange format.  This is also something I'm going to need soon.
>
> Named graphs are the beginnings of how to do this, and everything could be
> done through the fourth term in a quad.  However, this is likely to be
> cumbersome and I don't see current implementations actually solving the
> problem properly yet.
>
>
>
> In logic we assign symbols to statements all the time (~A & B), but not in
> a well defined way where each unique statement has exactly one canonical
> name.
>
> An interesting question, is whether two identical triples (edges) from
> different documents would share the same canonicalized form, or whether the
> provenance / named graph would need to be part of the canonicalization.
> More of a f(subject, predicate, object, graph) = <edge:graph#123wer234d23>
> where 123wer234d23 is a hash(subject, predicate, object).
>
>
> This is one good solution.  Another, applicable sometimes, is to just have
> serial numbers relative to some database.  One semantic web idiom is that
> the only unambiguous reference to a triple or set of triples is a complete
> restatement of those triples.  It is basically the same however to define a
> temporary term in a local context like A = {set of triples}, then make
> statements about A.  An externalized set should be able to do that and even
> reference a subset in a database elsewhere.
>
>
>
> One use case of for this (from Melvin) would be to apply weights to
> statements: { X :magnitude 10 } where X is a uri which identifies the
> statement { :Bob :trusts :Mary } .
>
>
> There are many cases where you need to describe provenance,
> trust/probability, and make statements about groups of statements.  It
> shouldn't be so hard or confusing.
>
>
> Best,
>
> Nathan
>
>
> sdw
>
>
Received on Wednesday, 1 August 2012 15:38:31 UTC

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