Homomorphisms into an Algebraically Closed Field

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Discussion Overview

The discussion revolves around the extension of embeddings from a field L into an algebraically closed field K, particularly focusing on algebraic extensions F of L. Participants explore the validity of extending embeddings in both finite and infinite cases, with references to Zorn's lemma and transfinite induction.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant questions whether the embedding of L into K can be extended to an algebraic extension F of L, noting certainty in the finite case but uncertainty in the infinite case.
  • Another participant asserts that the infinite case can be derived from the finite case using Zorn's lemma.
  • A subsequent reply seeks clarification on the application of Zorn's lemma in this context.
  • Another participant suggests an alternative approach using transfinite induction to construct the embedding incrementally.
  • A participant expresses a preference for Zorn's lemma and seeks guidance on its application for proving the existence of the desired map.
  • Discussion includes considerations of how to order the objects in the poset for Zorn's lemma to apply effectively.

Areas of Agreement / Disagreement

Participants express differing views on the methods for extending embeddings, with some favoring Zorn's lemma and others suggesting transfinite induction. The discussion remains unresolved regarding the specifics of applying these methods.

Contextual Notes

The discussion does not resolve the assumptions or definitions necessary for applying Zorn's lemma or transfinite induction, leaving open questions about the conditions under which the extension holds.

Spartan Math
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Okay, so I'm trying to finish of a problem on integral closure and I am rather unsure if the following fact is true:

If L embeds into an algebraically closed field K and F is an algebraic extension of L, then it is possible to extend the embedding of L to F into K.

Now the case where F is a finite extension of L is true, but not quite so sure about the infinite case.

Thoughts would be appreciated.
 
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Spartan Math said:
Now the case where F is a finite extension of L is true, but not quite so sure about the infinite case.
The infinite case follows from the finite one by an application of Zorn's lemma.
 
and how exactly does one do that?
 
If you're not a Zorn's Lemma type, then maybe you're a transfinite induction type? Adjoin elements of F to L one at a time, and construct F --> K one bit at a time. Mutter something about well-orderings so that this makes sense.
 
Well, I'm very much a Zorn's Lemma type, if you will. I just wasn't exactly sure how to go about using it.
 
Well, you want to prove the existence of a map from an algebraic extension of L to K, and you already know particular instances. So most naïvely, it seems you'd want the objects of your poset to be such maps.

Then, you'd need an ordering relation to say when one object L-->E-->K is "bigger" than another object L-->F-->K.
 

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