public function setMultiple( core_kernel_classes_Resource $resource, $isMultiple)
    {
        
    	$multipleProperty = new core_kernel_classes_Property(GenerisRdf::PROPERTY_MULTIPLE);
        $value = ((bool)$isMultiple) ?  GenerisRdf::GENERIS_TRUE : GenerisRdf::GENERIS_FALSE ;
        $this->removePropertyValues($resource, $multipleProperty);
        $this->setPropertyValue($resource, $multipleProperty, $value);
        
    }