- From: Sandro Hawke <sandro@w3.org>
- Date: Thu, 07 Jun 2001 17:02:51 -0500
- To: www-rdf-interest@w3.org
In http://lists.w3.org/Archives/Public/www-rdf-interest/2001Apr/0058.html (mid:200104100044.f3A0iJ701421@daniel.hawke.org) I gave a survey of ways to handle sequences (lists) in the RDF model. I'm personally comfortable with first/rest/empty lists, but I was trying to gather the options. Jos De Roo followed up at the time with a :list operator (which I *think* only works with his extended unflattenable interpretation of n3 contexts; ie not in the pure RDF model) and with Difference Lists. Difference Lists are indeed another nice form. They have the same first/rest structure as daml:lists, but instead of indicating the end of the list with the object "empty", you indicate it with any object. The "difference list" is then identified by the pair of the leading node (which has the first element as its "first") and the trailing node (which is pointed to as "rest" by the last data node, the one whose "first" is the last element in the list.) Anyway, I forgot Curry lists, which I think are similar to daml lists in most ways, except they use only N+1 RDF statements instead of 2*N to represent a list of N element. They are just a little weird in heavily using predicates as subjects, which may make some tools uncomfortable. I'm not sure how to express the range of the Currying predicate, for instance. I discuss this from another perspective in http://lists.w3.org/Archives/Public/www-rdf-logic/2001Jun/0153.html -- sandro
Received on Thursday, 7 June 2001 17:03:02 UTC