- From: Jonathan Borden <jonathan@openhealth.org>
- Date: Wed, 20 Mar 2002 11:59:20 -0500
- To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>, "Pat Hayes" <phayes@ai.uwf.edu>, <w3c-rdfcore-wg@w3.org>
- Cc: <www-webont-wg@w3.org>
Jeremy Carroll wrote: > > As I understand it, the minimal unasserted triple proposal is that at least > for daml:collection it would have been better if the triples with properties > daml:first and daml:rest (and maybe those ending rdf:type daml:List ), were > somehow special. To me the minimal proposal is to acknowledge that "dark triples" can be syntactically identified, and have a status in the MT. > > There is an intended syntactic restriction on these triples i.e. that each > cell in a daml:collection has: > - rdf:type daml:List (and no other) > - exactly one daml:first property (pointing to a resource) > - exactly one daml:rest property ( pointing to daml:nil or another cell ) > - no other properties. There are two perhaps at least partially, perhaps completely orthogonal issues: 1) recursive, closed, ordered syntax of daml:List 2) unasserted triples. > > My point being that using dark triples to construct purely syntactic > substructures within RDF graphs then begs the question of how to describe > the syntax of those syntactic substructures. Right, so (1) above describes a list, and (2) describes how the list is interpreted (or something to that effect) > > The various schema proposals appear to me to be a way of (indirectly) > constraining the syntax, and hence there is a win in terms of learning curve > if we don't need to duplicate at the metameta level what we are already > doing at the meta level. > > I am deliberatly sidestepping whether we want daml:collection to become > owl:collection. > There are several issues, perhaps "daml:collection" is not the best name, because it is a macro like parse type, which is applied to the object of a property, rather than a collection _class_ e.g. (using Qnames for URIrefs) <daml:Property rdf:about="daml:oneOf"> <rdfs:range rdf:resource="daml:List"/> </daml:Property> I have suggested that one can define two base properties "owl:set" and "owl:sequence" the first whose semantics _treat_ the daml:List value as a set, the second which treats it as a list (i.e. restricts the rdfs:range to daml:List). Appropriate OWL properties e.g. owl:oneOf, owl:insersectionOf, owl:disjointUnionOf etc. are <subPropertyOf> the appropriate "owl:set" or "owl:sequence" as the case may be. Now, whether the triples contained in the daml:List are to be asserted or unasserted is a different issue. Perhaps we need another pair of properties "owl:uset" and "owl:usequence" (or some other name) whose objects would be "unasserted". Is this analogous to "lambda" and "nlambda"? Jonathan
Received on Wednesday, 20 March 2002 12:03:47 UTC