- From: Axel Polleres <axel.polleres@deri.org>
- Date: Mon, 21 Jan 2008 17:20:52 +0000
- To: Hassan Aït-Kaci <hak@ilog.com>
- CC: axel@polleres.net, Christian de Sainte Marie <csma@ilog.fr>, Jos de Bruijn <debruijn@inf.unibz.it>, RIF <public-rif-wg@w3.org>
Hassan Aït-Kaci wrote: > Axel Polleres wrote: > >> whereas, on the contrary in frames, any slot can appear 0 or several >> times, i.e. >> >> person1[firstname -> "Christian", lastname -> "de Sainte Marie"] >> >> and >> >> person1[firstname -> "Christian"] AND person1[lastname -> "de Sainte >> Marie"] >> >> say the exactly same thing, i.e. mutually entail each other. > > What? You mean that there can be only one "person1" object named > "Christian"? no, I mean whether I write the frame formula in version one or version 2 above, it is the same thing. that has nothing to do with keys. person1 is the objectID ... maybe I should have written person1##person[firstname -> "Christian", lastname -> "de Sainte Marie"] and person1##person[firstname -> "Christian"] AND person1[lastname -> "de Sainte Marie"] to make this clearer. > IMHO, what you are describing corresponds to the notion > of database record key(s) - i.e., the attribute(s) that characterize > individual records. > > Furthermore, even if you do have a notion of keys (which we have > not discussed within RIF as far as I recall), there is still another > situation to take into consideration: just like algebraic (i.e., > positional) terms are built of symbols that may have (or not) > well-formedness constraints (e.g., signatures, typing, annotations, > etc...). To make things even more interesting, not everyone agrees > with one specific semantics for the very same frame syntax (i.e., do > we allow repeated "slots" - and in this case, is this an error or is > it that such a slot has as value the set (or some kind of aggregate) > of all the values for this slot. Some also allow mandatory as well > as non-mandatory attributes - some even allow any symbol as a slot > (i.e., unconstrained signatures). > > While the RIF BLD masterminds (i.e., the authors of the document: > Harold and Michael) give one possible semantics for these syntactic > constructs; but this semantics is not necessarily compatible with > many extant rule languages, several of which would wish to use the RIF. > > -hak -- Dr. Axel Polleres email: axel@polleres.net url: http://www.polleres.net/ rdf:Resource owl:differentFrom xsd:anyURI .
Received on Monday, 21 January 2008 17:21:12 UTC