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Subject: individual space vs class space (was: Re: [xdi] Minutes: XDI TCTelecon Thursday 1-2PM PT 2009-02-12)
Hello Markus, Drummond, thanks for this input; I think this is a good way to explore: information about instances of class should be somehow inside the xri. However, this again clashes with (probably my wrong understanding of) +x/+y/+x+y. In fact, =giovanni+ball would mean =giovanni/$has/+ball, thus =giovanni/+ball/=giovanni+ball. Indeed, =giovanni+ball is an instance. Well, this apparently might make sense, but consider a similar example: =drummond/$has/+friend thus =drummond/+friend/=drummond+friend would =drummond+friend be an instance, like =giovanni or =markus? =drummond/+friend/=giovanni =drummond/+friend/=markus In case not, what would be then the range of +friend? The strange aspect is that things would work fine without +x/+y/+x+y! Sorry, I'm probably still missing the real need to have this pattern in our model. Giovanni At 20.39 13/02/2009, Markus Sabadello wrote: Maybe the "class" ball should be +ball, and the "instance" ball should be =giovanni+ball or =markus+ball or =drummond+ball or simply =+ball ! Markus On Fri, Feb 13, 2009 at 7:37 PM, Giovanni Bartolomeo <giovanni.bartolomeo@uniroma2.it> wrote: Dear Drummond, Thanks for these detailed minutes. Let me check if I've understood correctly: In this example, let us assume that +ball/+color/+ball+color is a valid dictionary entry (class definition). Let suppose +aBall/$is$a/+ball (i.e. +aBall is an instance of +ball). Since +aBall inherits properties from +Ball, I can say +aBall/+color/+red, which is an "instance level" predicate. But I cannot say +aBall/+color/+ball+color (right?) Main question: would +aBall/+color/+aBall+color make any sense? Second question: how to know that +aBall is "an instance"? $is$a might also mean "subclassOf", right? Thanks (and sorry for being so obsessive on this topic, countless nights spent on this :-(, Giovanni At 06.34 13/02/2009, Drummond Reed wrote: We next discussed another concern of Giovanni's with some "strange" statements that can be made with $has. This is related to this email: http://lists.oasis-open.org/archives/xdi/200901/msg00054.html It is the example about balls and their colors, where +x is +ball and +y is +color. This produces the XDI RDF statement +ball/+color/+ball+color. But in the same document we have also +ball/+color/+red. So you have two different objects of the same predicate, which is fine in RDF, but one (=red) is an instance of color and the other (+ball+color) is a subclass of color. After some discussion, we realized that what was deceiving about these examples is that they confuse the dictionary/class space (Bill would say "T-box") from the individual/instance space ("A-box"). For example, in some email threads we had talked about having +ball/+color/+ball+color and +ball/+color/+red in the same graph. While this is technically possible, it doesn't make sense because the first statement is appropriate to a dictionary and the second would be more appropriate to an instance, except that +ball is not a typical instance. More typical would be =jbradley+ball/+color/+red.
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