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Subject: Re: [xdi] Minutes: XDI TC Telecon Thursday 1-2PM PT 2009-02-12
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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