On Thu, 27 Jan 2011 18:06:02 +0000, Michael Kay <>
wrote:
>> 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.
?? If the constraint is that sum(//order/@value) > 826 must be true,
then it follows that //order/@value must have at least one member.
Cheers
Rick Jelliffe
