# Prove the Cardinality of the Integers is the same as the Cardinality of the Odd Integers | Summary and Q&A

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September 23, 2020
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The Math Sorcerer
Prove the Cardinality of the Integers is the same as the Cardinality of the Odd Integers

## TL;DR

A proof is provided showing that the set of integers has the same cardinality as the set of odd integers.

## Key Insights

• 😫 The proof establishes a bijective function between the set of integers and the set of odd integers.
• 😫 Being a bijection, the function shows that the two sets have the same cardinality.
• 😫 This result demonstrates that the concepts of "number of elements" and "cardinality" can be used to compare infinite sets.
• 🦕 The proof highlights the importance of constructively defining the function and well-utilizing the properties of integers and odd numbers.
• 😫 Understanding bijections is crucial in establishing equivalences between different sets in mathematics.
• 😫 This proof builds on the foundational concepts of set theory and number theory.
• 🏑 The result has applications in various mathematical fields, including analysis, algebra, and topology.

## Transcript

in this problem we have to prove that the set of integers has the same cardinality as the set of odd integers let's go ahead and go through the proof so you basically have to find a bijection from the set of integers to the set of odd integers so we're going to let z be the set of integers so this is the typical notation for the set of integers and... Read More

### Q: What is the purpose of the proof?

The proof aims to show that the set of integers and the set of odd integers have the same number of elements, or cardinality.

### Q: How is the function defined to establish a bijection?

The function is defined as f(n) = 2n + 1, where n is an integer. It maps an integer to an odd integer.

### Q: What does it mean for a function to be one-to-one?

A one-to-one function, or injective function, ensures that if the function of two different inputs is equal, then the inputs must be equal as well.

### Q: What does it mean for a function to be onto?

An onto function, or subjective function, ensures that every element in the codomain is mapped to by at least one element in the domain.

## Summary & Key Takeaways

• The proof aims to establish a bijection between the set of integers and the set of odd integers.

• By defining a function that maps an integer to an odd integer, it is shown that the function is one-to-one and onto.

• The proof demonstrates that the sets of integers and odd integers have the same cardinality.