function testIsEqualToIgnoresNamespaceDifferences()
{
$s = 'http://example.com/people/bloggs-joe';
$rdfType = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#type';
$graph1 = new ExtendedGraph();
$graph1->add_resource_triple($s, $rdfType, 'http://xmlns.com/foaf/0.1/Person');
$graph2 = new ExtendedGraph();
$graph2->set_namespace_mapping('foaf', self::ONT_foaf);
$graph2->add_resource_triple($s, $rdfType, 'http://xmlns.com/foaf/0.1/Person');
$graph3 = new ExtendedGraph();
$graph3->set_namespace_mapping('FAF', self::ONT_foaf);
$graph3->add_resource_triple($s, $rdfType, 'http://xmlns.com/foaf/0.1/Person');
$this->assertTrue($graph1->is_equal_to($graph2), 'graph1 should equal graph2');
$this->assertTrue($graph2->is_equal_to($graph1), 'graph2 should equal graph1');
$this->assertTrue($graph2->is_equal_to($graph3), 'graph2 should equal graph3');
$this->assertTrue($graph3->is_equal_to($graph2), 'graph3 should equal graph2');
}