Re: inconcistency in CBD definition in Updated specification of Concise Bounded Descriptions

To reiterate your example:

Original RDF graph:

	x y _:1 .
	x z a .
	x b _:2 .
	_:1 c d .
	_:1 e "f" .

CBD for x (which happens to be the same as the original graph):

	x y _:1 .
	x z a .
	x b _:2 .
	_:1 c d .
	_:1 e "f" .

_:1 is an object node in the CBD for x.
_:1 is a blank node.
_:1 serves as a subject for a statement in the CBD for x (and thus as well
    in the original graph).




From: Richard Newman <r.newman@reading.ac.uk>
Subject: Re: inconcistency in CBD definition in Updated specification of Concise Bounded Descriptions
Date: Sun, 5 Jun 2005 14:38:12 +0100

> > How can
> >
> >     for all statements [included?] in the subgraph thus far having a
> >     blank node object, include in the subgraph all statements in the
> >     source graph where the subject of the statement is the blank node
> >     in question ...
> >
> 
> Original graph:
> x y [blank node 1];
>    z a.
> 
> x b [blank node 2].
> 
> [blank node 1] c d;
>                 e "f".
> 
> Initial subgraph (x is target):
> 
> x y [blank node 1].
> x z a.
> x b [blank node 2].
> 
> Initial graph contains:
> 
> [blank node 1] c d .
> [blank node 1] e "f".
> 
> So we add these.
> 
> ** No triples in the initial graph have [blank node 2] as their  
> subject. We stop. **
> 
> The subgraph now contains 5 triples, where the objects are all URIs,  
> literals, or blank nodes for which there are no statements in the  
> graph (not the subgraph, the _original_ graph) with that blank node  
> as the subject.

Not so.  _:1 is in the subgraph.  It is a blank node.  There is a statement
in the original graph (and in the subgraph) that has _:1 as its subject.

> I.e. the subgraph contains statements about object bnodes if any such  
> statements exist. If it contains triples pointing to bnodes, and no  
> statements about those bnodes, it's because the original graph didn't  
> make any statements about those bnodes.

This is not what is stated in the submission.

> -R
> 
> 
> >
> > and
> >
> >     This results in a subgraph where the object nodes are [...], or
> >     blank nodes not serving as the subject of any statement in the
> >     graph.
> >
> > possibly be reconciled?


Peter F. Patel-Schneider
Bell Labs Research

Received on Sunday, 5 June 2005 14:02:37 UTC