# countable

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Related to countably: Countably additive, Countably compact

## countable

[′kau̇nt·ə·bəl]
(mathematics)
Either finite or denumerable. Also known as enumerable.

## countable

(mathematics)
A term describing a set which is isomorphic to a subet of the natural numbers. A countable set has "countably many" elements. If the isomorphism is stated explicitly then the set is called "a counted set" or "an enumeration".

Examples of countable sets are any finite set, the natural numbers, integers, and rational numbers. The real numbers and complex numbers are not
References in periodicals archive ?
Thus, [iota] will be injective on [mathematical expression not reproducible] for all but countably many of the partitions P compatible with [[omega].sub.0].
In order to prove that F is a countably strict-set contraction, we first consider
A subset D of L is countably directed if every countable subset of D has an upper bound in D.
We remark that the functions in [V.sup.p] have lateral limits everywhere, and at most countably many discontinuities.
A subset of X is I-sequentially compact if and only if it is I-sequentially countably compact.
Using this and the definition of countably additive, we see that [zeta] [member of] [[SIGMA].sub.m] [PHI]([A.sub.m]) iff for all [epsilon] > 0, there exists some N [member of] N and points [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] with [m.sub.i] < N so that [absolute value of [[SIGMA].sub.i][y.sub.i] - [zeta]] < [epsilon].
When dealing with such problems, we are given a finite or countably infinite set of solutions from which we have to find the one that minimizes or maximizes the given function (Michiels et al.
For example, one can imagine such a "book" as being made up of a countably infinite collection of six-by-nine inch "leaves" lying parallel to the xy-plane and projecting rigidly from each rational point in the unit interval of the z-axis.
184), while, in every formal system, only countably many are available.
(1970): "Markets with Countably Many Commodities" International Economic Review, 11(3), 369-377.
Any infinite set with cardinal number [[omega].sub.1] can be expressed as a disjoint union of a class C of countably infinite sets, the cardinality of C being [[omega].sub.1].

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