[xsl] Efficient XPath 2.0 expression to return each <row> element for wh

Hi Folks,

I have a large XML document containing data about airports around the world:

<airports>
    <row>
        <navaid>A</navaid>
    </row>
    <row>
        <navaid>B</navaid>
    </row>
    <row>
        <navaid>A</navaid>
    </row>
</airports>

Notice that there is only one <row> element having the B navaid, but two <row> 
elements having the A navaid.

I want an XPath 2.0 expression to return each <row> element for which there are 
other <row> elements having the same navaid. For the above example, I want the 
XPath expression to return the first and third <row> elements.

Here is one way to do it:

//row[navaid = (preceding-sibling::row/navaid, following-sibling::row/navaid)]

Eek! That is horribly inefficient. I ran that XPath expression on my XML 
document and it took a long time to finish.

Is there an efficient XPath 2.0 expression to solve this problem? 

Note: I am running the XPath expression from Oxygen's XPath evaluator, not from 
an XSLT program.

/Roger
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