private function cancel( &$numerators, &$denominators )
	{
		if ( ! $denominators ) return;

		foreach ( $numerators as $key => $numerator )
		{
			$found = array_search( $numerator, $denominators );
			if ( $found === false ) continue;
			unset( $numerators[ $key ] );
			unset( $denominators[ $found ] );
		}
	}