A set is countable if: (1) it is finite, or (2) it has the same cardinality (size) as the set of natural numbers. Equivalently, a set is countable if it has the same cardinality as some subset of the set of natural numbers.Otherwise, it is uncountable.heorem: The set of all finite subsets of the natural numbers is countable. If you have a finite subset, you can order the elements into a finite sequence. There are only countably many finite sequences, so also there are only countably many finite subsets.
Rhinitis: Introduction. Rhinitis: Nasal lining inflammation leading to runny/blocked nose. More detailed information about the symptoms, causes, and treatments of Rhinitis is available below. Symptoms of Rhinitis
Perennial allergic rhinitis is caused by allergies to substances that are present year round. The chief causes of this type of rhinitis are allergies to dust mites, mold, animal dander and cockroach debris. Nonallergic rhinitis. Sometimes perennial rhinitis is not caused by allergic triggers.