B Extending the Fundamental Theorem of Arithmetic to the rationals

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The discussion revolves around extending the Fundamental Theorem of Arithmetic (FTA) to positive rational numbers by allowing integer exponents in prime factorization. While completeness is relatively easy to prove, the uniqueness of such representations raises questions, as distinct combinations of integers may yield the same rational number. Participants argue that the FTA fundamentally applies to integers and cannot be generalized to rational numbers without losing its meaning, as primes cannot be defined in the field of rational numbers. The consensus suggests that any rational number can be expressed as a ratio of products of primes, but this does not constitute a new theorem for rational numbers. Ultimately, the FTA remains a statement about integers, and its application to rationals is merely a reiteration of the theorem applied to numerators and denominators.
  • #31
Warp said:
I am not sure about the uniqueness, however. Could two different combinations of integers produce the same rational number?
Of course they can \frac{1}{2} and \frac{17}{34} represent the same rational number.

Rationals do not have a unique representation. Every rational number is a member of an equivalence class of combinations of integers.
 
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  • #32
Svein said:
Of course they can \frac{1}{2} and \frac{17}{34} represent the same rational number.

Rationals do not have a unique representation.
But they have a unique reduced form to lowest terms, p/q where GCD(p,q)=1. Then both p and q can be factored uniquely into primes where p and q have no common primes.
 
  • #33
FactChecker said:
But they have a unique reduced form to lowest terms, p/q where GCD(p,q)=1. Then both p and q can be factored uniquely into primes where p and q have no common primes.
The crucial point is the title. The word extension suggests a form of generalization, which it is not. You can't extend from ring to field. No way.
 
  • #34
fresh_42 said:
The crucial point is the title. The word extension suggests a form of generalization, which it is not. You can't extend from ring to field. No way.
There are some formally defined uses of the word "extension", but extending a theorem is not one of those.
In any case, the original question has probably been answered.
 
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  • #35
fresh_42 said:
The crucial point is the title. The word extension suggests a form of generalization, which it is not. You can't extend from ring to field. No way.
It is a generalization in the sense that it is a correct statement which includes unique factorization in the integers as a special case, not in the sense that it deals with prime elements in ##\mathbb{Q}.##
 
  • #36
An application of FTA is something basically different than an extension of FTA.

This is logically relevant as it is algebraically. To throw it all in one pot teaches the wrong motivations. A true statement isn't the same thing as a true classification. All posts above thought to an end would mean: Let's gather all theorems, list them in a book and call it: True. I cannot see how this is doing anyone a favor.
 
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