W3C home > Mailing lists > Public > public-rif-wg@w3.org > January 2007

Re: slotted notation -summary

From: Christian de Sainte Marie <csma@ilog.fr>
Date: Tue, 09 Jan 2007 15:16:00 +0100
Message-ID: <45A3A3A0.1010107@ilog.fr>
To: Michael Kifer <kifer@cs.sunysb.edu>
CC: "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>

Michael Kifer wrote:
>  [...]
> Different slotted styles
> ------------------------
> We can distinguish at least 2 styles of slotted notation: relational and
> object-oriented.

At least for those two ones, isn't it the case that a slotted predicate 
of the OO kind can always be represented as a conjunction of binary 
slotted predicates of the relational variety, where the predicate 
represents the slot/property/attribute, one of the roles is the object 
(e.g., the first, by convention), and the other one is the value?

> Object-oriented slot notation:
>           This semantics is used in F-logic, RDF, etc., and can also be
>           simulated by choosing the appropriate constraints for OSF.
>           Again, there are two things that one might say about slots in
>           F-logic (and RDFS):
> 	  p(slot1->val1,...,slotn->valn)
> 	        Here p is an object (as opposed to relation) and
> 		slot1(p)=val1, ..., slotn(p)=valn.

That is, couldn't that be, by convention (in RIF):
    slot1(p, val1) and ... and slotn(p, valn)?

I may be naive, but I did not see in the discussion anything that could 
not be handled that way (except maybe for RDF bNodes).

So, why not have the closed relational slotted notation in RIF Core, and 
some convention for transforming OO slotted predicated into that 
notation (same kind of process as the one to bring an OSF term into its 
solved form)? (*)

I am aware that that solution might have an impact on roundtrips (and, 
thus, on efficiency in specific rule engines; readibility in specific 
target rule languages etc), but that would be an argument in favor of 
having data-model specific dialects, rather than having two different 
notations (**) for the same thing in RIF Core.

On the other hand, if the two notations (**) are not equivalent, and if 
there is no single notation (with a single semantics) that can account 
for both kind of slotted syntaxes (***), we should probably not have 
slots in RIF Core (that is, Michael's option 4).

(*) that would not imply a closed-world assumption, if I am correct.

(**) 1) n-ary slotted predicate where the predicate is actually the 
object; 2) binary slotted predicates where the predicate is the 
attribute, and the arguments the object and the value.

(***) what other semantics are there for slotted syntaxes? How do they 
relate to the relational and OO ones?

Received on Tuesday, 9 January 2007 14:15:21 UTC

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