• To: xml-dev@l...
• Subject: Re: XPath and XSD/RNG
• From: "Robert C. Lyons" <boblyons@u...>
• Date: Wed, 01 Jun 2005 20:23:04 -0400
• Cc: stefan.tilkov@i...
• In-reply-to: <1117657238.3338.ezmlm@l...>
• References: <1117657238.3338.ezmlm@l...>
• User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7.2) Gecko/20040803

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

• Prev by Date: Faster XML (was: Why XML for Messaging?)
• Next by Date: Re: Why XML for Messaging?
• Previous by thread: [ANN] YesLogic Prince 5.0 beta 1
• Next by thread: XPath question with regards to Schematron rule
• Index(es):
  • Date
  • Thread