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Some issues around RDF Collections and containers

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Wed, 28 Jul 2004 10:11:21 +0100
Message-ID: <41076DB9.7050601@hp.com>
To: RDF Data Access Working Group <public-rdf-dawg@w3.org>

Collections:

1/ Getting the whole list

Getting the whole list requires traversing an arbitrary, unknown length 
structure of RDF graph nodes.  Fixed conjunctive/disjunctive patterns 
can't express this.  See also (3).

This is compounded by lists often being comprised of bNodes.

2/ Asking if something is contained in a list

Testing whether some resource/literal is in a list is hard with fixed 
patterns because you need to enumerate the possibilities.

3/ Unusual structures

While most RDF collections are regular rdf:first/rdf:rest/rdf:nil 
cons-cell structures, there is no restriction imposed for, say two 
rdf:first's on one slot, or multiple tails to the list, or tails that 
join up (well - OK - all tails join up at rdf:nil!)

Containers:

RDF containers are easier to deal with if there is the inference support 
to provide rdfs:member.  But they still can have unusual structures like 
two rdf:_1 elements or gaps in their numbering.

	Andy
Received on Wednesday, 28 July 2004 05:12:09 GMT

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