What is Kronecker's theorem/lemma for root solutions?

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Discussion Overview

The discussion centers around Kronecker's theorem or lemma related to root solutions of polynomials, particularly in the context of odd prime degree polynomials and its implications for Abel's Theorem regarding the impossibility of solving the quintic equation by radicals. Participants explore various resources and proofs related to this theorem, as well as its connections to Galois theory.

Discussion Character

  • Technical explanation
  • Exploratory
  • Homework-related

Main Points Raised

  • One participant references an article discussing Kronecker's contributions to the understanding of odd prime degree polynomials and their relationship to Abel's Theorem.
  • Another participant suggests that if there are multiple zeros in a field extension, it implies the existence of an intermediate field with those zeros, leading to a contradiction based on the prime degree of the splitting field.
  • A repeated point emphasizes the same reasoning about the implications of having multiple zeros in a field extension.
  • One participant provides a link to a document on Galois theory that may contain relevant proof, mentioning a specific formula related to field extensions.
  • A textbook is cited as containing a proof of Kronecker’s Theorem, along with a summary of its implications for solving polynomials by radicals.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the specifics of Kronecker's theorem or the proof details, and multiple viewpoints and resources are presented without resolution of disagreements.

Contextual Notes

Some statements rely on assumptions about field extensions and the properties of Galois groups, which may not be universally accepted or fully explored within the discussion.

swampwiz
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I am going through this article, and it mentions a Kronecker made a discovery about odd prime degree polynomials that makes Abel's Theorem on the impossibility of the quintic easier to prove:

https://hubpages.com/education/Abel...oduction-to-the-Sublime-Beauty-of-Mathematics

Obviously, Kronecker has produced a lot of mathematical work, and I find it hard to find his proof on this.
 
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If we had more than one zero in a field extension, then there would be a field in between with those zeros and no others of degree greater than two. But the total degree of the splitting field is prime and the degree of the smaller field would be a divisor of that prime. Thus there can only be one zero or already all.
 
fresh_42 said:
If we had more than one zero in a field extension, then there would be a field in between with those zeros and no others of degree greater than two. But the total degree of the splitting field is prime and the degree of the smaller field would be a divisor of that prime. Thus there can only be one zero or already all.

Hi, do you have link that discusses the proof for this?
 
The textbook, https://danboak.files.wordpress.com/2017/08/afirstcourseinabstractalgebra.pdf, by Marlow Anderson and Todd Feil, has a proof of Kronecker’s Theorem, and uses and discusses it extensively.

Summary for Chapter 48 Solving Polynomials by Radicals:
In this chapter we prove that if a polynomial over a subfield of the complex numbers can be solved by radicals, then the Galois group of its splitting field over the base field is necessarily a solvable group. We can then easily exhibit a fifth degree polynomial over the rational numbers that cannot be solved by radicals.​
 

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