public function getSecondExpression()
    {
        $returnValue = null;

        
        if(empty($this->secondExpression)){
	        $property = new core_kernel_classes_Property(RulesRdf::PROPERTY_SECOND_EXPRESSION);
			$this->secondExpression = new core_kernel_rules_Expression($this->getUniquePropertyValue($property)->getUri());
        }
        $returnValue = $this->secondExpression;
        

        return $returnValue;
    }