Stefan Tilkov wrote:
"Is there a way to check whether an XPath expression could possibly be
true for a document conforming to a particular W3C XML Schema (or
Relax NG schema) without having access to the document? Is this
something that toolkits support?
E.g. if the schema disallows /root/element/subelement, the XPath
expression /root/element/subelement[0] cannot yield a non-null result
for any conforming document."
Stefan,
It's not possible to write a general algorithm that determines
whether or not an XPath expression could possibly be true
for all documents that conform to a schema. This problem is
undecidable. Also, the problem of whether or not an XPath
expression is satisfiable is undecidable.
For more details, please see:
http://www.idealliance.org/papers/extreme03/html/2003/Lyons01/EML2003Lyons01.html
Best regards,
Bob Lyons
XML and Java Consultant
www.unidex.com
