In both XPath 1.0 and 2.0 you can use:
//article[number(translate(@pub-date,'-','')) > 20101115]
Your XPath 2.0 expression is correct, using Saxon 9.0.3 this transformation:
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xsl:template match="/">
<xsl:sequence select="//article[xs:date(./@pub-date) > xs:date('2010-11-15')]"/>
</xsl:template>
</xsl:stylesheet>
when applied on the provided XML document:
<root>
<article title="wired" pub-date="2010-11-22" />
<article title="Plus 24" pub-date="2010-11-22" />
<article title="Finance" pub-date="2010-10-25" />
</root>
produces the wanted, correct result:
<article title="wired" pub-date="2010-11-22"/>
<article title="Plus 24" pub-date="2010-11-22"/>
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