From: Christian de Sainte Marie <csma@ilog.fr>

Date: Tue, 09 Jan 2007 16:12:16 +0100

Message-ID: <45A3B0D0.8090904@ilog.fr>

To: Michael Kifer <kifer@cs.sunysb.edu>

CC: "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>

Date: Tue, 09 Jan 2007 16:12:16 +0100

Message-ID: <45A3B0D0.8090904@ilog.fr>

To: Michael Kifer <kifer@cs.sunysb.edu>

CC: "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>

Michael, your reply confuses me; you seem to think that I propose to keep the OO slotted notation and transform the expressions in relational slotetd notation into OO slotted notation, whereas I am proposing the reverse. See details and, hopefully, clarifications below. Michael Kifer wrote: >>>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? > > Relational slotted notation cannot be conveniently represented this way. In > Relational notation the Id of the object is implicit and cannot be > manipulated by the language. I apologize if I was not clear: all my email is about transforming *from* OO slot notation *to* relational slotted notation. This requires making the reference to the object explicit as one of the arguments of each of the resulting binary predicates, indeed. > [...] >> >>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)? (*) > > You want to map the relational slotted notation to the OO slotted notation > - not the other way around. Relational slotted notation implies that object > Ids are inaccessible, while OO notation assumes that they are. So, you can > map OO to relational slots in a certain sense. Hmmm... Isn't that what I am talking about? I propose that we consider only the relational slotted notation for RIF Core, if needed; and that we tranform, by convention, any expression in OO slotted notation into conjunctions of binary relational predicates. My question whether this is always feasible can also be stated as: does the OO slotted notation p(slot1->val1,...,slotn->valn) say anything different than that the object p is in binary relation with (at least, if we are in an open world) each of the values val1 to valn, binary relations that we could name slot1 to slotn? > I am not sure that such a mapping makes good sense for our purposes. After > all, one can translate slotted notation into positional notation as well. > By this argument we can just leave positional stuff and nothing else. Right. Actually, I asked in another posting what was the motivation for relational slotted notation. I can think of typing. > Yes. We can take the OO notation or leave both of them out for dialects. I meant: have the relational notation or leave both of them out. >>(**) 1) n-ary slotted predicate where the predicate is actually the >>object; > > In relational slotted notation the predicate is NOT an object, but a class. > (Please reread my comparison to get this cleared up.) Right. I understood that much. I was talking of OO slotted notation. Sorry if it was not clear. ChristianReceived on Tuesday, 9 January 2007 15:11:37 GMT

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