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rules se1/2

From: pat hayes <phayes@ai.uwf.edu>
Date: Mon, 2 Jun 2003 17:48:58 -0500
Message-Id: <p0521062abb017b593dd8@[10.0.100.24]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-rdf-comments@w3.org

Ive rewritten the statement of the existential instantiation rules as follows:

----------
se1

aaa ppp bbb .   |-    aaa ppp _:nnn .

where _:nnn is a blank node associated with bbb.

se2

aaa ppp bbb .  |- _:nnn ppp bbb .

where _:nnn is a blank node associated with aaa.


The terminology 'associated with' means that the blank node must be 
either be a 'new' node which does not occur in the graph, or else it 
must be a blank node created by an earlier application of either of 
these rules on the same URiref, blank node or literal aaa or bbb. 
This rather complicated condition ensures that the resulting graph 
obtained by adding the new blank-node triples has the original graph 
as an instance and that all such graphs can be generated by these 
rules; the association between introduced blank nodes and the URIref, 
blank node or literal that they replace provides the instance 
mapping. For example, the graph

<ex:a> <ex:p> <ex:b> .
<ex:c> <ex:q> <ex:a> .

could be expanded as follows

_:x <ex:p> <ex:b> . by se1 using a new _:x associated with ex:a
<ex:c> <ex:q> _:x . by se2 using the same _:x associated with ex:a
_:x <ex:p> _:y . by se2 using a new _:y associated with ex:b

-----

I think this covers the point you raised. Thanks for noticing the bug.

Pat

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Received on Monday, 2 June 2003 18:49:01 GMT

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