How about internationalization? If the subject is a literal, how would translations be associated?
On Jul 1, 2010, at 5:14 , Pat Hayes wrote: > > On Jun 30, 2010, at 8:14 PM, Ross Singer wrote: > >> I suppose my questions here would be: >> >> 1) What's the use case of a literal as subject statement (besides >> being an academic exercise)? > > A few off the top of my head. > > 1. Titles of books, music and other works might have properties such as the > date they were registered, who owns them, etc.. > 2. Dates may have significant properties such as being the day that someone > was shot or when war broke out. > 3. Dates represented as character strings in some known date format other > than XSD can be asserted to be the same as a 'real' date by writing things > like > > "01-02-1481" sameDateAs "01022010"^^xsd:date . > "01-02-1481" isDateIn :MuslimCalendar . > > I am sure that you can think of many more. In general, allowing strings as > subjects opens the door to a wide range of uses of RDF to 'attach' > information to pieces of text. Another example which occurs to me: this piece > of text is the French translation of that piece of text, expressed as a > single RDF triple with two literals. > > 4. It has been noted that one can map datatyping into RDF itself by treating > the datatypes as properties, and there are several use cases for this. The > natural way to do it involves having literals as subject, since the dataype > map goes from the string to the value: > > "23" xsd:number "23"^^xsd:number . > > 5. Also, allowing this "purely academically" has the notable advantage of > simplifying RDF(S) inferencing, including making the forward-chaining rules > simpler. Right now, there is a strange oddity involving blank node > instantiations. One can say things like 'the number of my children is prime" > by using an blank node: > > :PatHayes hasNumberOfKids _:x . > _:x :a :PrimeNumber . > > But this legal RDF can't be instantiated in the obvious way: > > :PatHayes hasNumberOfKids "3"^^xsd:number . > "3"^^xsd:number :a "PrimeNumber . XXXX > > This trips up RDFS reasoners, which can often produce inferences by a kind of > sneaky use-a-bnode-instead maneuver even when the obvious conclusion cannot > be stated because of the restriction. (There are a few examples in the RDF > semantics document.) Removing the restriction would enable reasoners to work > more efficiently with a smaller set of rules. (I gather that at least some of > the RDFS rule engines out there already do this, internally.) > >> 2) Does literal as subject make sense in "linked data" (I ask mainly >> from a "follow your nose" perspective) if blank nodes are considered >> controversial? > > Seems to me that from the linked data POV, anything that can be an object > should also be useable as a subject. Of course, that does allow for the view > that both of them should only ever be IRIs, I guess. > > Pat Hayes > >> > > > -- Dr. Axel Rauschmayer axel.rauschma...@ifi.lmu.de http://hypergraphs.de/ :: Hyena: connected information manager, free at hypergraphs.de/hyena/ ::
