Some issues around RDF Collections and containers

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