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Re: [xml-dev] Is Anyone Interested In XPath 2.0 Use Cases or Requiremen

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```At 02:08 8/7/02, David Carlisle wrote:
>Yes of course. If you want value based set equality that's
>  not(\$b[. != \$a]) and not(\$a[. != \$b])

Um... (thinks, scribbles in *scratch*, checks spec)

ITYM
not(\$b[not(. = \$a)]) and not(\$a[not(. = \$b)])

No?

\$b[. = \$a] returns all X in \$b such that there is some Y in \$a for which X = Y

\$b[. != \$a] returns all X in \$b such that there is some Y in \$a for which X
!= Y

\$b[not(. = \$a)] returns all X in \$b such that there is no node Y in \$a for
which X = Y

In other words, if the three nodes in \$b have values "1", "2", and "3", as
do the three nodes in \$a:

\$b[. = \$a] will return 3 nodes, because for each node X in \$b, there is a
node Y in \$a with the same value.

But \$b[. != \$a] will *also* return 3 nodes, because for each node X in \$b,
there is a node Y in \$a with a *different* value.

(I know David knows this, but I wanted to convince myself... see the note
in §3.4 of XPath 1.0 if curious for details.  David's solution will work if
\$a and \$b each have only one node.)

~Chris
--
Christopher R. Maden, Principal Consultant, crism consulting
DTDs/schemas - conversion - ebooks - publishing - Web - B2B - training