Cory,
(01)
Yes. There are better ways to represent assertions than RDF. But when the
required language for the project is RDF, you play the cards you are dealt.
(02)
Note: We know exactly which statements are embedded in assertions. Those are
the ones that are not necessarily taken to be true. And those are the ones for
which we use named graphs. As I said, one can use named graphs as a means of
representing assertions -- the fact that X said sentence S.
(03)
One should also distinguish assertions from provenance metadata. That is, the
source of what is taken to be a fact is a different kind of information from
the fact that X said S. But adding metadata to RDF is about repository
features, not semantic content.
(04)
-Ed
(05)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of Cory Casanave
> Sent: Wednesday, June 11, 2014 5:19 PM
> To: [ontolog-forum]
> Subject: Re: [ontolog-forum] Requesting Opinions on the Benefits of
> Predicates as Nodes
>
> Ed,
> Very true - but that assumes you KNOW you will want to make a statement
> about that triple (or set of triples) in the graph. It doesn't work in the
>general
> case. Also, a zillion named graphs would blow up the infrastructures.
> -Cory
>
> > -----Original Message-----
> > From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> > bounces@xxxxxxxxxxxxxxxx] On Behalf Of Barkmeyer, Edward J
> > Sent: Wednesday, June 11, 2014 5:04 PM
> > To: [ontolog-forum]
> > Subject: Re: [ontolog-forum] Requesting Opinions on the Benefits of
> > Predicates as Nodes
> >
> > Jack,
> >
> > We also manage assertions. This is one of the reasons why the RDF
> > folk invented RDF Named Graphs -- a bucket of triples with an identifier.
> >
> > -Ed
> >
> > > -----Original Message-----
> > > From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> > > bounces@xxxxxxxxxxxxxxxx] On Behalf Of Jack Park
> > > Sent: Wednesday, June 11, 2014 2:23 PM
> > > To: [ontolog-forum]
> > > Subject: Re: [ontolog-forum] Requesting Opinions on the Benefits of
> > > Predicates as Nodes
> > >
> > > I'd like to mention one other 'modeling' situation:
> > >
> > > Consider this sentence:
> > >
> > > A majority of scientists believe that X causes Y.
> > >
> > > In that, we can see two triples, one of which is nested as object in the
> other.
> > >
> > > In my work, I grant identity to assertions. In simplest RDF, that
> > > means granting an ID to a triple, which makes it a quad. But, since
> > > my assertion (predicate instance) already has identity, nested
> > > triples can be created directly.
> > >
> > > I'm not saying that's the only way to do such modeling; nested
> > > conceptual graphs also make sense.
> > >
> > > On Wed, Jun 11, 2014 at 10:29 AM, Mark H Linehan <mhl@xxxxxxxxxxx>
> > > wrote:
> > > > Jack describes here an important aspect of relationships that is
> > > > not directly
> > > captured in graphs that treat the predicates as edges: the
> > > attributes associated with the relationships. Consider the triple
> > > {CompanyX employs Person1} using a predicate called "employs". The
> > > triple implicitly describes what an English speaker would
> > > conceptualize as an "employment", with attributes such as "start
> > > date", "end date", a location, etc. In RDF, you have to reify the
> > > relationship to associate such attributes. In UML, you could use an
> > > association class for
> > this. In SBVR, you can define an "employment"
> > > concept (with its attributes) and say that every instance of "employs"
> > > is an instance of "employment". These approaches are needed so they
> > > can support queries such as "who is employed at xyz location", as
> > > well as "what is the employment location of Person1").
> > > >
> > > > Making predicates into first-class components of a graph certainly
> > > > helps
> > > model the "objectification" aspects of relationships. Even more
> > > important is to permit the predicates to relate more than just
> > > subject and object, so as to directly associate the attributes.
> > > >
> > > > Mark H. Linehan
> > > > www.linkedin.com/in/MarkHLinehan
> > > > -----Original Message-----
> > > > From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
> > > > [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Jack
> > > > Park
> > > > Sent: Wednesday, June 11, 2014 12:21 PM
> > > > To: [ontolog-forum]
> > > > Subject: Re: [ontolog-forum] Requesting Opinions on the Benefits
> > > > of Predicates as Nodes
> > > >
> > > > I see an additional benefit, but not necessarily affiliated with
> > > > the way you
> > > describe an 'implicit node' -- where a predicate appears, still, to
> > > be a second- class citizen in the graph.
> > > >
> > > > Let me explain.
> > > >
> > > > Mostly, it would seem that a predicate in a triple performs the
> > > > task of
> > > linking subject and object; it has no other reason for being there
> > > other than to complete the assertion, e.g. A relates to B.
> > > >
> > > > But, consider this: if a specific *instance* of a predicate exists
> > > > as a
> > > connective between two objects, then it can be said to carry the
> > > full semantics of the assertion itself. The instance is not an 'implicit'
> > > node: it is a vertex like any other in a graph.
> > > >
> > > > If I say: A cause B, then the node which is the 'cause' predicate
> > > > can carry
> > > the full semantics of the triple itself. It's not just your father's
> > > predicate anymore; it's a first class citizen.
> > > >
> > > > Why do I care?
> > > >
> > > > Consider that said predicate has entails a possibly complex biography.
> > > > Who discovered it? What evidence supports it? What debates are in
> > > > play
> > > about it?
> > > >
> > > > I can't assign or otherwise link that biography to either A or B,
> > > > but only to
> > > the specific predicate that ties them together.
> > > >
> > > > If I might add, I will assert that predicates as first class
> > > > citizens is perhaps
> > > the only difference between an RDF graph and a topic map.
> > > > I've built topic maps with RDF using the BigData RDF store; they
> > > > work just
> > > fine, can import and export from, e.g. OWL documents, but with a
> > > loss of information when the topic map becomes OWL.
> > > >
> > > >
> > > > On Wed, Jun 11, 2014 at 8:59 AM, Frank Guerino
> > > <Frank.Guerino@xxxxxxxxx> wrote:
> > > >> Hi All,
> > > >>
> > > >> For a number of years, we've been working with Data Driven
> > > >> Synthesis as a means of rapidly generating Data Networks/Graphs
> > > >> and the Knowledge Constructs (e.g. Library Catalogs, Indexes,
> > > >> Taxonomies, Visualizations,
> > > >> etc.) that help humans make easier & better sense of them (If
> > > >> interested, see NOUNZ). Like many other Graph representations,
> > > >> we use "triples" or "triplets" to help represent Semantic
> > > >> Relationships, where descriptive Predicates are used as the
> > > >> binding between Subject
> > > Nodes and Object Nodes.
> > > >>
> > > >> To date, we've only treated Subjects and Objects as "Nodes" but
> > > >> we've always known that we can (and have planned to) implement
> > > >> and treat Predicates as a special type of "implicit" Node, as well.
> > > >> (Time didn’t' allow us to get to doing so, until now.) We
> > > >> believe that doing so grants users of Graphs certain benefits.
> > > >> We've identified three (3)…
> > > >>
> > > >> #1: The first and obvious advantage is that users can now enter a
> > > >> Graph from any Edge/Predicate as easily as they can enter from
> > > >> any Node, and start to traverse the Graph based on that point of
> entry.
> > > >>
> > > >> #2: The second advantage of treating Predicates as Nodes is that
> > > >> a Predicate can now be used as an "Index" or "Pointer" that
> > > >> allows users to quickly find all Nodes which are tied to said
> > > >> Predicate (or any Predicates that match certain traits). In
> > > >> other words, it's a way of asking the Graph to quickly identify
> > > >> all Nodes that are connected to a specific Edge/Link/Predicate
> > > >> (or any of a common set of Predicate traits). This means that,
> > > >> in addition to being able to ask "Node-oriented" questions of the
> > > >> Graph, you can now also ask "Predicate/Edge-oriented" questions of
> the Graph, as well.
> > > >> This leads to even more complex scenarios of being able to ask
> > > >> questions of,
> > > both, Nodes and Edges.
> > > >>
> > > >> #3: The third advantage (based on the second) is that traversal
> > > >> of a Graph can be even quicker, leading to even shorter paths,
> > > >> because instead of only traversing a Graph from
> > > >> Node-to-Node-to-Node, through Nodes, users can now traverse from
> > > >> any Edge/Predicate to any other Edge/Predicate, through
> Edges/Predicates.
> > > >>
> > > >> My question to the Community: Aside from the above three, do you
> > > >> see any other benefits that we're missing?
> > > >>
> > > >> Thanks for your help.
> > > >>
> > > >> My Best,
> > > >>
> > > >> Frank
> > > >> --
> > > >> Frank Guerino, Chairman
> > > >> The International Foundation for Information Technology (IF4IT)
> > > >> http://www.if4it.com
> > > >> 1.908.294.5191 (M)
> > > >>
> > > >>
> > > >>
> > >
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(06)
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