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Re: New Terminology Section

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Sat, 7 May 2016 06:14:35 -0700
To: Holger Knublauch <holger@topquadrant.com>, "public-data-shapes-wg@w3.org" <public-data-shapes-wg@w3.org>
Message-ID: <88ee90cf-c0bf-54fa-5c9a-7e1daea674ab@gmail.com>
On 05/06/2016 09:54 PM, Holger Knublauch wrote:
> 
> On 7/05/2016 2:14, Peter F. Patel-Schneider wrote:
>> I think that instead of reiterating descriptions from RDF 1.1 Concepts and
>> Abstract Syntax, and having errors in at least one of the descriptions, it
>> would be better to just defer to that document.
> 
> Where is the error? The definitions of terms like node and triples are just
> meant to be links to the RDF spec.

The definitions of terms like node and triples are definitely different from
RDF 1.1 Concepts and Abstract Syntax.  Here are just two examples that I
noticed at first glance.

1/ An RDF triple does not consist of three nodes.
2/ It is RDF terms that can be IRIs, literals, or blank nodes, not nodes.  RDF
does not define a notion of a node outside of the nodes of an RDF graph.

Each and every time new wording is used to describe existing notions there is
a decided chance for an inconsistency to be introduced.  It is safer, and
better, to just say something like

This document uses "RDF graph", "RDF triple", "IRI", "literal", "blank node",
"node" of an RDF graph, "RDF term", and "subject", "predicate", and "object"
of RDF triples as defined in Section 3 of RDF 1.1 Concepts and Abstract Syntax.

Similarly for other notions from RDF and RDFS that are used in SHACL.

>> I think that it is a bad idea to redefine terms from RDF and RDFS.  Like it or
>> not, some readers of SHACL documents will use the RDF and RDFS definitions of
>> terms like subclass and superclass when reading SHACL documents even if these
>> terms are redefined in the SHACL documents.
> 
> The goal of this terminology section was to divide and conquer the problem
> space so that we have specific small snippets to work on. Everyone is welcome
> to contribute here. Pointing out that something is "a bad idea" needs to be
> followed by a specific suggestion on what to do instead. We already spoke at
> length about not using terms from RDFS if they have different meaning in
> SHACL. You suggested using "SHACL instance" instead of "instance" etc. If that
> is still your suggestion, I have no problem switching to that term within the
> spec (although I doubt anybody will ever use these terms elsewhere and that it
> would make a difference in practice). The CSS styling of underlining each use
> of these terms to go back to their definition should also help.
> 
> But if someone has better terms for "instance", "class", "subclass" and
> "type", then please make suggestions. My role as an editor is not to create
> the whole content, but to reflect what the WG has decided.

My view is that instead of introducing new notions that use the same words or
phrases as notions from RDF and RDFS SHACL should use new phrases, e.g., SHACL
instance.   I have been very clear about this throughout.

> 
> Holger

peter
Received on Saturday, 7 May 2016 13:21:18 UTC

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