Re: Tricky XPath Question

Subject: Re: Tricky XPath Question
From: disco <disco@xxxxxxxxxxxxxxx>
Date: Wed, 1 Dec 1999 15:46:46 -0500 (EST)
> <xsl:for-each select="term[not(preceding::term=.)]">
>   <xsl:value-of select="."/>
> </xsl:for-each>

Okay, I understand this, but it leaves me wondering about the algebra
sitting behind XPath. I would have thought that the equality relation on
node sets was "for all" (ie. for all elements in node set A, all elements
in node set B are equal to each of them) but instead it is "for at least
one" (ie. for at least one element in node set A, there is at least one
element equal to it).

This is confirmed by the spec: (S3.4) "If both objects to be compared are
node-sets, then the comparison will be true if and only if there is a node
in the first node-set and a node in the second node-set such that the
result of performing the comparison on the string-values of the two nodes
is true." But it leaves me curious whether standard query algebra (eg. the
relational algebra, used in RDBMS) had much influence on the language.

Regardless, thanks for the help.

Dan


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