Re: a blank node issue

Le 02/03/2011 20:52, Pat Hayes a écrit :
>
> [...] Bnodes have local scope, a syntactic issue rather than a semantic one.

Strange. I would have said the opposite. Syntactically, scope has no 
importance and even has no meaning, unless maybe if you forbid a name to 
appear in two contexts (but this is obviously not the case in RDF).
An RDF graph is a set of triples which is composed of URIs (elements of 
an infinite set), literals (an infinite set disjoint from URIs) and 
bnodes (an infinite set disjoint from URIs and Literals).

Syntax-wise, this is all we have (in 2004 standard). The scope of URIs 
and bnodes could even be swapped (make URIs local and bnodes global) and 
the syntax would stay identical. Nothing in the syntax specifies the 
scope of these elements. The semantics does. Note that this is true in 
other languages like programming languages, but sometimes, programming 
languages have additional syntactical constraints such as the obligation 
to declare a variable within a context, which makes scope more explicit. 
But think of less constrained languages like javascript, visual basic, 
PHP...

 > [...]

-- 
Antoine Zimmermann
Researcher at:
Laboratoire d'InfoRmatique en Image et Systèmes d'information
Database Group
7 Avenue Jean Capelle
69621 Villeurbanne Cedex
France
Lecturer at:
Institut National des Sciences Appliquées de Lyon
20 Avenue Albert Einstein
69621 Villeurbanne Cedex
France
antoine.zimmermann@insa-lyon.fr
http://zimmer.aprilfoolsreview.com/

Received on Thursday, 3 March 2011 14:50:35 UTC