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Re: Is everything blank?

From: pat hayes <phayes@ihmc.us>
Date: Fri, 6 Jun 2003 16:30:21 -0500
Message-Id: <p05210600bb06b62cb94d@[10.0.100.24]>
To: Seth Russell <seth@robustai.net>
Cc: jimbobbs@hotmail.com, www-rdf-logic@w3.org

>pat hayes wrote:
>
>>
>>>  > Not sure what you mean. Certainly, it would be possible to take any
>>>
>>>>  OWL triple (Using Ntriples notation):
>>>>
>>>>  ex:foo ex:Property ex:baz
>>>>
>>>>  and replace it with
>>>>
>>>>  _:x ex:Property ex:baz
>>>>  _:x owl:sameIndividualAs ex:foo
>>>>
>>>>  and the two are equivalent. And since they are, the second form is
>>>>  kind of confusing (not wrong, but confusing) since one might easily
>>>>  think, when reading it, why didn't they just write the first one?
>>>
>>>
>>>I was thinking that a node is some abstract thing, and the name (URI,
>>>QName, whatever) of a node is a property of the node.
>>
>>
>>No, that was one way to understand RDF graphs, and it used to be 
>>the 'official' way, but we realized a while ago that there was 
>>really no need to distinguish between URIrefs and literals and the 
>>nodes they 'labelled', so the official line now is that in these 
>>cases the URIref or literal *is* the node.
>
>
>Certainly the node is not identical to the URIref string.

The graph node is the URIref, yes.  In the above example the graph 
contains two triples, containing a total of three nodes, which are a 
blank node (indicated by _:x in the Ntriples notation) and two 
URIrefs, ex:baz and ex:foo. The URIrefs *are* the object nodes of the 
triples. The word 'node' is in fact redundant, but has been retained 
for consistency with older usage and as an implicit reference to the 
use of nodes and arcs in diagramming the RDF graphs in illustrations.

>   I cout two propositions in the node identified by "_:x" above and 
>one in the node identified by "ex:foo" above.  I count zero 
>propositions in the URIref "ex:foo".    Can't make sense that way .. 
>well ok lets assume that the URIref that your talking about is not 
>the string ... ok ... it's instead what the URIref denotes (the 
>thing itself).

No, the URIref is a piece of syntax, cf. RFC 2396. I was talking 
about the graph syntax, not what it denotes.

>But that thing that the URIref denotes has perhaps zillions of 
>propositions from perhaps zillions of points of view and does not 
>even exist in the plain of our data where the URIref string is in 
>our computer.

I have absolutely no idea what you are talking about in this 
sentence, I'm afraid.

>  To me it seems like your are advocating the classical confusion 
>between map and territory ... but I'm sure that your would not make 
>that mistake .. so how am I to make sense of your sentence "the 
>URIref or literal *is* the node" ?

It is purely a description of the syntax. In Korzybskian terms, its 
all about the maps, not mentioning the territory at all. In a genuine 
cartographic metaphor, consider a map convention where instead of 
writing a 'city' symbol and labelling it with the city name, you just 
write the city name on the map where the city is located. Then you 
might say, the city symbol (= node) *is* the city name.

Hope this helps.

Pat
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Received on Friday, 6 June 2003 17:38:24 GMT

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