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