[xsl] Seek XPath 2.0 expression for this: Are there any book titles with more than one binding?

["Costello, Roger L. costello@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Hello XPath experts!

At the bottom of this message is my XML document. I need an XPath 2.0
expression that returns the result of this query:

	Are there any book titles with more than
	one binding? If yes, then show the first book
	for each binding.

For the below XML document, the query should return these two books:

<Book>
    <Author>Sally Smith</Author>
    <Title>XYZ</Title>
    <Binding>hardcover</Binding>
    <Count>1</Count>
    <Description>lo lo lo ..</Description>
</Book>
<Book>
    <Author>Sally Smith</Author>
    <Title>XYZ</Title>
    <Binding>softcover</Binding>
    <Count>1</Count>
    <Description>do do do ..</Description>
</Book>

Notice that the two books have the same author and title but different binding
(hardcover versus softcover).

This XPath 2.0 expression seems to work:

for $i in /Bookstore/BookTitle/Book[1],
    $j in /Bookstore/BookTitle/Book[1] return
        if (($i ne $j)
            and ($i/Author eq $j/Author)
            and ($i/Title eq $j/Title)
            and ($i/Binding ne $j/Binding)
            and ($i = $j/preceding::Book))
        then ($i, $j)
        else ()

That expression seems awfully complicated. Is there a simpler expression? If
there isn't a simpler expression, then do you see anything missing in the
expression (i.e., something that the expression doesn't take into
consideration)?  /Roger

<Bookstore>
    <BookTitle>
        <Book>
            <Author>John Doe</Author>
            <Title>ABC</Title>
            <Binding>hardcover</Binding>
            <Count>1</Count>
            <Description>da da da ..</Description>
        </Book>
        <Book>
            <Author>John Doe</Author>
            <Title>ABC</Title>
            <Binding>hardcover</Binding>
            <Count>2</Count>
            <Description>za za za ..</Description>
        </Book>
    </BookTitle>
    <BookTitle>
        <Book>
            <Author>John Doe</Author>
            <Title>Foo</Title>
            <Binding>softcover</Binding>
            <Count>1</Count>
            <Description>na na na ..</Description>
        </Book>
    </BookTitle>
    <BookTitle>
        <Book>
            <Author>Sally Smith</Author>
            <Title>XYZ</Title>
            <Binding>hardcover</Binding>
            <Count>1</Count>
            <Description>lo lo lo ..</Description>
        </Book>
        <Book>
            <Author>Sally Smith</Author>
            <Title>XYZ</Title>
            <Binding>hardcover</Binding>
            <Count>2</Count>
            <Description>ho ho ho ..</Description>
        </Book>
    </BookTitle>
    <BookTitle>
        <Book>
            <Author>Sally Smith</Author>
            <Title>XYZ</Title>
            <Binding>softcover</Binding>
            <Count>1</Count>
            <Description>do do do ..</Description>
        </Book>
    </BookTitle>
</Bookstore>