Is a Bounded Set in R Countable if it Can be Covered by an Epsilon Cover?

In summary, to prove that a given set A (subset of real numbers) is countable, it is necessary to show that the set is bounded and for any real number x, there exists an epsilon such that the intersection of the set A with the interval (x-eps, x+eps) is countable. One way to do this is by covering the set with open intervals and using the compactness of a closed interval containing the set.
  • #1
sayan2009
14
0

Homework Statement



given a set A(subset of R(reals)) is bounded.and for all x belongs to R there exists epsilon(eps) such that {(x-eps,x+eps) intersection A} is countable..to prove A is countable

Homework Equations





The Attempt at a Solution

...bdd set in R is totally bounded...but iam not finding the way how to cover A by epsilon cover(has at most countable elements)
 
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  • #2
Take a closed interval C containing A and cover it with open intervals having a countable intersection with A. Now use the compactness of the closed interval C.
 
  • #3
oooooooooooo gr888888888...thanks
 

What is a countable bounded set?

A countable bounded set is a collection of elements that can be counted and has a finite upper bound or limit. This means that there is a maximum value or size for the elements in the set.

How is a countable bounded set different from an unbounded set?

A countable bounded set has a finite upper bound, while an unbounded set does not have a limit or maximum value for its elements. This means that the elements in an unbounded set can continue indefinitely without reaching a maximum value.

What is an example of a countable bounded set?

An example of a countable bounded set is a set of natural numbers between 1 and 10. This set has a finite upper bound (10) and can be counted (1, 2, 3, 4, 5, 6, 7, 8, 9, 10).

Can a countable bounded set be infinite?

No, a countable bounded set cannot be infinite. As mentioned, a countable bounded set has a finite upper bound, which means that the number of elements in the set is limited and cannot continue indefinitely.

How is a countable bounded set related to the concept of cardinality?

The cardinality of a set refers to the number of elements in the set. A countable bounded set has a finite cardinality because the number of elements in the set is limited. This is in contrast to an unbounded set, which has an infinite cardinality.

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