denumerable

English

The word was introduced around the beginning of the 20th century, from Latin denumerare (“to count out”) +‎ -able.

denumerable (not comparable)

(mathematics) Capable of being assigned a bijection to the natural numbers. Applied to sets which are not finite, but have a one-to-one mapping to the natural numbers.
The empty set is not denumerable because it is finite; the rational numbers are, surprisingly, denumerable because every possible fraction can be assigned a natural number and vice versa.

单词	denumerable
释义	denumerable English Etymology The word was introduced around the beginning of the 20th century, from Latin denumerare (“to count out”) +‎ -able. Adjective denumerable (not comparable) (mathematics) Capable of being assigned a bijection to the natural numbers. Applied to sets which are not finite, but have a one-to-one mapping to the natural numbers. The empty set is not denumerable* because it is finite; the rational numbers are, surprisingly, denumerable because every possible fraction can be assigned a natural number and vice versa.* Synonyms countable countably infinite Derived terms denumerability See also countable set uncountable set
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