rdf:firts and rdf:rest as functional property

>From the description of RDF collections in the primer I would consider
rdf:first and rdf:rest as functional properties. However,

http://www.w3.org/TR/rdf-schema/#ch_list says:
> Note: RDFS does not require that there be only one first element of a
> list-like structure, or even that a list-like structure have a first
> element.

I understand that RDFS doesn't have the notion of functional properties,
but it could nevertheless be specified specifically for rdf:first and

Especially since RDFS also states that:

> A triple of the form:
> L rdf:rest rdf:nil
> states that L is an instance of rdf:List that has one item; that item
> can be indicated using the rdf:first property

I'm not sure if this means that the last element has exactly or at least
one item. In any case to me this seems to be a rather weird
special-casing of the last rdf:List in a structure.

My questions:
- Are there useful usages where an rdf:list has several distinct
rdf:first and rdf:rest value?
- Is it just not written that rdf:first and rdf:rest are functional
(maybe due to some spec layering reasons) or is false to consider
rdf:first and rdf:next as functional?


Received on Wednesday, 18 February 2009 11:38:09 UTC