Cardinality of Real Numbers & Irrationals: Prove They're Equal

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In summary, the cardinality of real numbers and irrational numbers is denoted by |R| or c, representing the number of elements in these sets. This can be proven through Cantor's diagonal argument, and is important in understanding the concept of infinity and sets. Other sets with equal cardinality to the real numbers include the set of algebraic numbers and the set of transcendental numbers, showcasing the different levels of infinity that exist.
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mathgeek808
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Need help with this proof:
Prove that the set of irrational numbers has the same cardinality as the set of real numbers.
 
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I would do this by a bijection. Pick a countable set A in the irrational numbers (think cosets if you can't come up with an example). Then construct a bijection that is the identity outside of A
 
  • #3
I would use arithmetic of cardinal numbers myself.
 
  • #4
The reals are the disjoint union of rationals and irrationals. Take this back to Hurkyl's suggestion.
 

What is the Cardinality of Real Numbers?

The cardinality of real numbers is the number of elements or points in the set of real numbers, denoted by |R| or c. It represents the size or magnitude of the set.

What is the Cardinality of Irrational Numbers?

The cardinality of irrational numbers is also denoted by |R| or c. This means that the number of elements in the set of irrational numbers is equal to the number of elements in the set of real numbers, making their cardinalities equal.

How do you prove that the Cardinality of Real Numbers and Irrational Numbers are equal?

This can be proven using Cantor's diagonal argument, which states that for any infinite set, the cardinality of its power set is greater than the cardinality of the set itself. Since the set of irrational numbers is a subset of the set of real numbers, their cardinalities must be equal.

Why is it important to prove the equality of Cardinality of Real Numbers and Irrational Numbers?

Proving the equality of these two cardinalities is important in understanding the concept of infinity and sets. It also helps to establish the concept of uncountability, where certain sets have infinitely many elements that cannot be counted.

Are there other sets with equal cardinality to the Real Numbers?

Yes, there are other sets with equal cardinality to the real numbers, such as the set of algebraic numbers and the set of transcendental numbers. This shows that there are different levels of infinity, all of which have equal cardinalities.

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