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Comment on the Dataset proposal (syntax)

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Thu, 26 Apr 2012 17:30:09 +0200
Message-ID: <4F996A01.4060601@emse.fr>
To: Richard Cyganiak <richard@cyganiak.de>
CC: RDF WG <public-rdf-wg@w3.org>
Hi,


(This email is mostly for Richard's attention)

Putting aside the discussion on dataset semantics, I have a few comments 
on the way the dataset proposal is described in terms of syntax:


"The RDF data model expresses information as graphs consisting of 
triples with subject, predicate and object."

The word "graph", in the RDF specifications, should never appear alone 
like this. It is well known that a graph is a pair (V,E) where V is a 
set of vertices and E is a set of edges. This is not what RDF Graphs 
are. RDF Graphs are not graphs, in any of the accepted mathematical 
definition of the term. We already agreed that the word "graph" alone is 
ambiguous and we resolved to use the phrase "RDF Graph" whenever we talk 
about sets of triples.

SUGGESTION:
"The RDF data model expresses information as RDF Graphs consisting of a 
set of triples with subject, predicate and object."

-----

"Often, one wants to hold multiple RDF graphs and record information 
about each graph, allowing an application to work with datasets that 
involve information from more than one graph."

SUGGESTION:
"... each RDF Graph, ... than one RDF Graph."

To sound less redundent, "hold multiple RDF graphs and record 
information about each one, ..."

-----

"An RDF Dataset represents a collection of graphs. An RDF Dataset 
comprises one graph, the default graph, which does not have a name, and 
zero or more named graphs, where each named graph is identified by an IRI."

Maybe say "distinguished RDF Graph":

SUGGESTION:
"An RDF Dataset comprises one distinguished RDF Graph, the /default 
graph/, which does not have a name, ..."

Moreover, the word "identified" may be missinterpreted.

SUGGESTION:
"..., where each named graph associates an IRI with an RDF Graph."

-----

"An RDF Dataset may contain zero named graphs; an RDF Dataset always 
contains one default graph."

SUGGESTION:
add "The default graph MAY be empty."

-----

Maybe a definition for "named graph" could be given before the formal 
definition of RDF Dataset:

SUGGESTION:
"A /named graph/ is a pair (n,g) where n is an IRI called the /graph 
name/ and g is an RDF Graph."

-----

"Formally, an RDF dataset is a set:

{ G, (<u1>, G1), (<u2>, G2), . . . (<un>, Gn) }

where G and each Gi are graphs, and each <ui> is an IRI. Each <ui> is 
distinct."

"... are RDF Graphs, ..."

----

"G is called the default graph. The pairs (<ui>, Gi) are called named 
graphs."

If "named graph" is defined before, it could look like this:

SUGGESTION:
"G is called the default graph. The pairs (<ui>, Gi) are named graphs."
-- 
Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
158 cours Fauriel
42023 Saint-Étienne Cedex 2
France
Tél:+33(0)4 77 42 83 36
Fax:+33(0)4 77 42 66 66
http://zimmer.aprilfoolsreview.com/
Received on Thursday, 26 April 2012 15:31:26 UTC

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