ZF Axiom of Infinity: Natural Numbers Exist

In summary, the ZF Axiom of Infinity is a fundamental axiom of set theory that states the existence of a set containing all natural numbers. This axiom is important because it provides a foundation for the construction and use of natural numbers in mathematics. It is also related to the Peano axioms, as it is used to prove them. The axiom cannot be proven and is accepted without proof in the Zermelo-Fraenkel set theory. While there are alternative axioms for the existence of natural numbers, the ZF Axiom of Infinity is the most widely used and accepted.
  • #1
CRGreathouse
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In ZF, the axiom of infinity says that the set of natural numbers exists. I was wondering if there was a (finitist?) weakening of ZF that included the axiom "the class of natural numbers exists".
 
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  • #2
Wait, this is a dumb question, isn't it. This actually follows from a suitable definition of classes and ZF - the axiom of infinity.

Sorry. :redface:
 

1. What is the ZF Axiom of Infinity?

The ZF Axiom of Infinity is a fundamental axiom of set theory, which states that there exists a set that contains all natural numbers.

2. Why is this axiom important?

This axiom is important because it provides a foundation for the construction of the natural numbers and ensures that they exist as a set. It also allows for the development of mathematical theories and proofs involving the natural numbers.

3. How does this axiom relate to the Peano axioms?

The ZF Axiom of Infinity is one of the axioms used to prove the Peano axioms, which are a set of axioms that define the properties of the natural numbers. The Peano axioms are built upon the ZF Axiom of Infinity.

4. Can this axiom be proven?

No, the ZF Axiom of Infinity cannot be proven. It is one of the axioms that is accepted without proof in the Zermelo-Fraenkel set theory, which is one of the most commonly used foundations for mathematics.

5. Are there any alternative axioms for the existence of natural numbers?

Yes, there are alternative axioms for the existence of natural numbers, such as the Axiom of Infinity in the Von Neumann-Bernays-Gödel set theory. However, the ZF Axiom of Infinity is the most commonly used and accepted axiom for this purpose.

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