Arrays in SKOS: proposal

Hi all,

Having reviewed all of the discussion on the issue of arrays and node
labels, I would like to go with the following addition to the SKOS schema:

----------------------------
skos:Array		a	rdfs:Class;	
	rdfs:label	'Array';
	rdfs:comment	'An array is either an ordered or an unordered
collection of concepts.  Arrays can be used for example to organise a set of
concepts according to some characteristic of division, primarily for visual
display.'
.

skos:array		a	rdf:Property;
	rdfs:label	'array';
	rdfs:domain	skos:Concept;
	rdfs:range		skos:Array;
	rdfs:comment	'Use this property to connect a concept to an array
of narrower concepts.  The narrower and broader statements involving the
parent concept and the members of the array should still be maintained
independently of the array construct.'
.

skos:members	a	rdf:Property;
	rdfs:label	'members';
	rdfs:domain	skos:Array;
	rdfs:comment	'Use this property to connect the array node to the
first member of an RDF list of concepts and/or arrays.';

skos:ordered	a	rdf:Property;
	rdfs:label	'order is significant';
	rdfs:domain	skos:Array;
	rdfs:range		xsd:Boolean;
	rdfs:comment	'Use this property to indicate whether the ordering
of an array of concepts is significant, and hence should be preserved by
applications, or is not significant and can be ignored.'
.
-----------------------------

By default, without using arrays, the ordering of narrower concepts is not
preserved by RDF applications.  Therefore, in any situation where the
ordering of a set of concepts is significant, an array should be used to
express that ordering.  The array may be given a label, but this is not
necessary.

The skos:Array construct is recommended for encoding the grouping of a set
of concepts according to some 'characteristic of division'.  In the majority
of cases of the use of characteristics of division, the ordering is
signficant.  Applications handling a skos:Array should treat the ordering as
significant by default.  

However, in some cases the ordering of concepts under a characteristic of
division is not significant.  It is recommended that a SKOS encoding of a
thesaurus does not introduce ordering information where such information was
not a part of the original thesaurus.  In these cases, the fact that the
ordering is irrelevant should be expressed by adding a
(skos:ordered,'false') property to the array.

An array may be a member of another array.  In this way arrays may be
nested.  

Any objections?

Al. 








---
Alistair Miles
Research Associate
CCLRC - Rutherford Appleton Laboratory
Building R1 Room 1.60
Fermi Avenue
Chilton
Didcot
Oxfordshire OX11 0QX
United Kingdom
Email:        a.j.miles@rl.ac.uk
Tel: +44 (0)1235 445440

Received on Thursday, 13 May 2004 11:41:15 UTC