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Re: reworded requirements for section 3 Complex Constraints

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Fri, 06 Feb 2015 05:39:02 -0800
Message-ID: <54D4C3F6.2020603@gmail.com>
To: Eric Prud'hommeaux <eric@w3.org>
CC: "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>
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On 02/05/2015 11:57 PM, Eric Prud'hommeaux wrote:
> * Eric Prud'hommeaux <eric@w3.org> [2015-02-06 01:56-0500]
>> In ShapeRequirements, I've reworked the definitions in 2.5 in terms of 
>> shapes. Below is a simplified diff of the differences. With Holger's 
>> approval, I'll make these changes and then remove the shapes/classes 
>> objections.
> 
> I've reworded the requirements for Complex Constraints. The first patch
> below replaces the umbrella requirement for Complex Constraints with a
> specific requirement for Constraint Extensions because having umbrella
> requirements is confusing and because that requirement appeared to be
> about extensibility. The rest are re-definitions of existing
> requirements. Again, with Holger's approval, I'll make these changes.
> 
> 
> --- Requirements/Complex Constraints	2015-02-06 02:50:54.408836654 -0500 
> +++ ShapeRequirements/Complex Constraints	2015-02-06 02:50:54.416832654
> -0500 @@ -1,3 +1,5 @@ === Complex Constraints ===
> 
> -The language should allow users to implement constraints that check
> complex conditions, with an expressivity as covered by the following
> sub-requirements (e.g. basic graph patterns, string and mathematical
> operations and comparison of multiple values). +==== Constraint
> Extensions ==== + +Shapes will have a defined extension mechanism
> enabling other languages to provide supplementary constraints, (e.g.
> basic graph patterns, string and mathematical operations and comparison
> of multiple values).

I see this as an unwelcome change.  This section is not about extension
mechanisms, it is instead about expressivity.  If there is to be an
extension mechanism it should be in a separate section.


> @@ -27,5 +29,5 @@
> 
> ==== Expressivity: Non-Existence of Patterns ====
> 
> -Many constraints require that a certain pattern does not exist in the
> graph. +Shapes will constraint on the absense as well as the presence of
> arcs.
> 
> @@ -37,5 +39,5 @@
> 
> ==== Expressivity: String Operations ====
> 
> -Some constraints require building new strings out of other strings, and
> building new URIs out of other values. +Shapes will provide string and
> URI manipulation.
> 
> @@ -47,5 +49,5 @@
> 
> ==== Expressivity: Language Tags ====
> 
> -Some constraints require comparing language tags of RDF literals, e.g.
> to check that no language is used more than once per property. Also to
> produce multi-lingual error messages. +Shapes will constrain on presence
> and uniqueness of language tags.
> 
> @@ -57,5 +59,5 @@
> 
> ==== Expressivity: Mathematical Operations ====
> 
> -Some constraints require mathematical calculations and comparisons, e.g.
> area = width * height. +Shapes will provide numeric manipulation.
> 
> @@ -67,5 +69,5 @@
> 
> ==== Expressivity: Literal Value Comparison ====
> 
> -Some constraints require operators such as <, <=, != etc, either against
> constants or other values that are dynamically retrieved at query time.
> Includes date/time comparison. +Shapes will provide numeric and date
> comparison.
> 

The new wording for most of these is too terse.  What are these facilities
to be used for?


peter
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Received on Friday, 6 February 2015 13:39:31 UTC

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