public function getTerminalExpression()
    {
        $returnValue = null;

        
        $property = new core_kernel_classes_Property(RulesRdf::PROPERTY_TERMINAL_EXPRESSION);
        $propertyValue = $this->getUniquePropertyValue($property);
        if ($propertyValue instanceof core_kernel_classes_Resource ) {
       		$returnValue = new core_kernel_rules_Term($propertyValue->getUri() );
        	$returnValue->debug = __METHOD__;	
        }
        else {
        	throw new common_Exception('property retrieve should be a Resource');
        }
        

        return $returnValue;
    }