In
mathematics, a
set is called finite if there is a
bijection between the set and some set of the form {1, 2, ..., n} where n is a
natural number. (The value n = 0 is allowed; that is, the
empty set is finite.) An
infinite set is a set which is not finite.Equivalently, a set is finite if its
cardinality, i.e., the number of its elements, is a natural number. More specifically, a set whose cardinality is n is also called an
n-set. For instance, the set of
integers between −15 and 3 (excluding the end points) has 17 elements, so it is finite; in fact, it is a 17-set. In contrast, the set of all
prime numbers has cardinality
ℵ0, so it is infinite.
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