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Re: What class of grammars is an XPath?

• From: Michael Kay <mike@saxonica.com>
• To: xml-dev@lists.xml.org
• Date: Thu, 27 Jan 2011 18:06:02 +0000

> The particular expression that Michael brought up -- 
> sum(//order/@value) > 826 -- certainly implies an open language (the 
> document must have at least one //order/@value).


Um, no: the expression is perfectly well-defined on a document that 
contains no orders (it's been a slack week, where are all the 
customers?). There's some kind of implication that the expression is 
designed to work on documents containing zero or more orders, but that's 
all we can say.

Michael Kay
Saxonica

• Follow-Ups:
  • Re: What class of grammars is an =?UTF-8?Q?XPath=3F?=
    • From: rjelliffe <rjelliffe@allette.com.au>

• References:
  • Which algorithm do XML Schema validators use to decide if a stringmatches a regular expression?
    • From: "Costello, Roger L." <costello@mitre.org>
  • Re: Which algorithm do XML Schema validators use to decideif a string matches a regular expression?
    • From: Michael Kay <mike@saxonica.com>
  • What class of grammars is an =?UTF-8?Q?XPath=3F?=
    • From: rjelliffe <rjelliffe@allette.com.au>
  • Re: What class of grammars is an XPath?
    • From: Dimitre Novatchev <dnovatchev@gmail.com>
  • Re: What class of grammars is an XPath?
    • From: Michael Kay <mike@saxonica.com>
  • Re: What class of grammars is an =?UTF-8?Q?XPath=3F?=
    • From: rjelliffe <rjelliffe@allette.com.au>