W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > September 2002

syntax and semantics

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Mon, 23 Sep 2002 13:44:36 +0300
Message-ID: <007401c262ee$35be07e0$d74416ac@NOE.Nokia.com>
To: "w3c-rdfcore-wg" <w3c-rdfcore-wg@w3.org>


I wanted to briefly recap a proposal that I've alluded to in 
various recent posts, lest it get lost in the mix...

Regarding tidyness the relation of syntactic and semantic equality:

1. Two nodes which may not be semantically equal must have distinct
   labels (i.e. inline literals must be given unique labels)

2. All nodes with identitical labels are syntactically tidy in the
   abstract graph, and thus are semantically equal.

3. Two nodes which do not have identical labels are not necessarily
   semantically unequal. Equality may be determined based on additional
   knowledge elsewhere in the graph or outside the scope of the RDF MT.

4. Applications may presume syntactic node intersection as equality 
   of meaning.

5. Applications may not presume syntactic node inequality as inequality 
   of meaning.

Thus:

Case 1a:

   aaa bbb _:x"foo" .
   ccc bbb _:y"foo" .

does not entail

   aaa bbb _:z .
   ccc bbb _:z .

but does not mean _:x"foo" != _:y"foo"

Case 1b:

   aaa bbb _:x"foo" .
   ccc bbb _:y"foo" .
   bbb rdfs:range ddd .

entails

   aaa bbb _:z .
   ccc bbb _:z .

Case 2a:

   aaa bbb <http://foo.com/bar>"xx" .
   ccc bbb <http://foo.com/bar>"xxx" .

does not entail

   aaa bbb _:z .
   ccc bbb _:z .

but does not mean <http://foo.com/bar>"xx" != <http://foo.com/bar>"xxx"

Case 2b:

   aaa bbb <http://foo.com/bar>"xx" .
   ccc bbb <http://foo.com/bar>"xx" .

entails

   aaa bbb _:z .
   ccc bbb _:z .

[Patrick Stickler, Nokia/Finland, (+358 50) 483 9453, patrick.stickler@nokia.com]
Received on Monday, 23 September 2002 06:48:49 EDT

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