RE: [xsl] Wath is the opposite of the union operator?

Subject: RE: [xsl] Wath is the opposite of the union operator?
From: "Michael Kay" <mike@xxxxxxxxxxxx>
Date: Thu, 22 Sep 2005 12:49:38 +0100
> Subject: [xsl] Wath is the opposite of the union operator?
> 
> Or puting it in another way, how do i select a group of nodes selected
> by some xpath expression EXCEPT the ones that are selected by another
> xpath expression?

The operation you are referring to is usually called "set difference". In
XPath 2.0, the operator is spelt "except".  There is also a set intersection
operator spelt "intersect". There's no equivalent to these in XSLT 1.0,
though some processors support the EXSLT set:difference() and
set:intersection() functions. You can expensively code 

A except B =>

   A[count(.|B) != count(B)]

A intersect B =>

   A[count(.|B) = count(B)]

Michael Kay
http://www.saxonica.com/

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