- From: Peter F. Patel-Schneider <pfps@inf.unibz.it>
- Date: Wed, 03 May 2006 08:54:03 -0400 (EDT)
- To: bry@ifi.lmu.de
- Cc: public-rif-wg@w3.org
From: Francois Bry <bry@ifi.lmu.de> Subject: Re: [RIF] Reaction to the proposal by Boley, Kifer et al Date: Wed, 03 May 2006 14:21:28 +0200 > Peter F. Patel-Schneider wrote: > > > >> This is based on a known logic: infinite Herbrand interpretations. > >> > > > > Reference, please. > > I could maybe help in giving reference if I would understand what you > are asking for. A reference to logics based on infinite Herbrand intepretations that shows how they relate to standard first-order logics. > How existentially quantified expressions are evaluated in relational > databases, in deductive databasesw, and in logic progreamming is > well-known, could be seen as "folklore knowledge". My guess is that you > have a precise question in mind -- that I do not know. In logics where every "domain element" has a name, the substitution interpretation of quantifiers is well known. However, how does this relate to logics where there is not necessarily a name for every domain element or where there cannot be a name for every domain element? > > I worry about situations like the following. > > > > Suppose that there (only) are two constants, T and F, and (only) one > > one-place function, N. Does it then follow from the following two facts > > > > N(T) = F > > N(F) = T > > > > that > > > > Ax Ey x = N(y) > > > > > > [...] > > > Not in logic programming, relational databases, and deductive databases > that have function symbols but not full treatment of equality. Of > course, a full treatment of equality can be considered/added. The proposal has a treatment of equality. I was expecting it to be a "full treatment", so I didn't see that there was anything to consider/add. > >>> I worry about the connection between the proposal and RDF and OWL. I do > >>> not view it as appropriate to relegate existing Semantic Web languages to > >>> an add-on query interface. > >>> > >> Why? > >> > > > > Because we are supposed to be working within the confines of the Semantic Web. > > I share this worry. However, marrying logic programming and RDF is > however surely feasible and challenging. Marrying logic programming and > OWl in some way is also surely possible and challenging. > > Is it really? It instead seems to me to be much more like a ghetto. In > > particular, the proposal uses a ternary predicate for RDF triples, > > divorcing RDF facts like ex:a rdf:type ex:b from a representation > > as ex:b(ex:a). > > > To the best of my understanding, the one and the other syntax are both > possible. Personally, I would prefer a syntax (subject predicate object) > because it is natural and simple. Is this a (single) ternary predicate? If not, how does it match the proposal? If so, how can it be considered to be natural? > I agree that integrating RDF/OWL through queries pose more problems than > it might first seem. Well many of these issues have already been brought up in discussions within the working group, so it is not as if they are somehow invisible. > François Peter F. Patel-Schneider
Received on Wednesday, 3 May 2006 12:54:28 UTC