Counting infinite sequence of sets

In summary, the conversation discusses the concept of countability and how the union of an infinite sequence of countable sets is also countable. The term "countable" is defined as having a bijection with the set of natural numbers, represented by the symbol N. The proof for this concept is similar to the proof for showing that the Cartesian product of two countable sets is also countable.
  • #1
ihatewonders
3
0
Let K1, K2, K3, . . . be an infnite sequence of sets, where each set Kn is countable.
Prove that the union of all of these sets K = Union from n=1 to infinity, Kn is countable.

I tried to start, but I don't even understand the question

Need some idea on how to start
 
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  • #2
Not understanding the question is not a good start. What does 'countable' mean?
 
  • #3
Denumerable?

The set K would be denumberable if there is a bijection ZZ+->K

by the way, can you teach me how to read "Bijection ZZ+->K?" ZZ+ is the symbol for all positive integer, -> is the arrow pointing to the set K.
and I have trouble understanding what F: NN -> A mean intuitively
 
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  • #4
I don't know what you are talking about. What does ZZ+->X mean? Countable means there is a bijection with N, the natural numbers. This is basically the same proof as showing NxN is countable. How do you do that?
 
  • #5
I'm sorry, >.< but what does NxN mean? is it the symbol for natural number?
 

1. What is an infinite sequence of sets?

An infinite sequence of sets is a mathematical concept that refers to a collection of sets arranged in a specific order, where each set in the sequence contains infinitely many elements. This means that the sequence continues indefinitely and there is no final set in the sequence.

2. How do you count an infinite sequence of sets?

Counting an infinite sequence of sets can be done by assigning each set in the sequence a unique number or label. This is similar to how we count the natural numbers (1, 2, 3, etc.) or the real numbers (1.1, 1.2, 1.3, etc.). However, since the sequence is infinite, the counting will also continue indefinitely.

3. Can all infinite sequences of sets be counted?

No, not all infinite sequences of sets can be counted. Some sequences are uncountable, meaning that there is no way to assign a unique number or label to each set in the sequence. An example of an uncountable sequence is the real numbers between 0 and 1.

4. Is there a limit to how many sets can be included in an infinite sequence?

No, there is no limit to how many sets can be included in an infinite sequence. As long as the sets are arranged in a specific order and each set contains infinitely many elements, the sequence can continue indefinitely.

5. What is the significance of counting infinite sequences of sets in science?

Counting infinite sequences of sets is important in mathematical analysis, which is used in many scientific fields such as physics, engineering, and economics. It allows us to study and understand continuous, infinite processes and phenomena in a precise and rigorous way.

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