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Paper on symmetry of XPath axes

From: Holger Meuss <meuss@cis.uni-muenchen.de>
Date: Mon, 11 Feb 2002 16:46:04 +0100 (CET)
Message-ID: <15463.59196.427434.569959@loihi.cis.uni-muenchen.de>
To: www-xpath-comments@w3.org
Dear colleagues,

my colleagues and I investigated the issue of symmetry in XPath axes
(and therefore the question which axes are redundant) in a research
paper recently submitted for publication. Possibly this paper is of
interest in the actual discussion which XPath axes shall be supported
by the standards using XPath, or in XPath 2.0. We would be happy to
hear comments from you on this paper. 
You can find the paper (PDF) at 


and an abstract at the end of this mail.




The location path language XPath is of particular importance for XML
applications since it is a core component of many XML processing
standards such as XSLT or XQuery.  In this paper, based on axis
symmetry of XPath, equivalences of XPath 1.0 location paths involving
reverse axes, such as ancestor and preceding, are established.
These equivalences are used as rewriting rules in an algorithm for
transforming location paths with reverse axes into equivalent
reverse-axis-free ones.  Location paths without reverse axes as
generated by the presented rewriting algorithm enable efficient
SAX-like streamed data processing of XPath.
Received on Monday, 11 February 2002 10:46:06 UTC

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