Infinite ring with exactly two non trivial maximal ideals

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Discussion Overview

The discussion revolves around the existence of an infinite ring that has exactly two non-trivial maximal ideals. Participants explore various examples and constructions related to this concept.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant, LiKeMath, inquires about the existence of an infinite ring with exactly two maximal ideals.
  • Another participant suggests \(\mathbb{R} \times \mathbb{R}\) as a potential example, but questions how multiplication is defined in this context.
  • A follow-up clarifies that multiplication in \(\mathbb{R} \times \mathbb{R}\) is defined pointwise: \((a,b) \cdot (c,d) = (ac, bd)\).
  • One participant proposes a construction involving the integers and rational numbers, suggesting that by inverting certain elements, the only maximal ideals remaining would be (2) and (3).
  • Another similar construction is mentioned involving continuous functions on the interval [0,1], where inverting functions that do not vanish at the endpoints would lead to maximal ideals that vanish at those points.
  • A participant references micromass's example, discussing continuous functions on a two-point set, where the maximal ideals correspond to functions vanishing at either point.

Areas of Agreement / Disagreement

The discussion does not reach a consensus on a definitive example of an infinite ring with exactly two maximal ideals, and multiple competing views and constructions are presented.

Contextual Notes

Participants explore various constructions and examples, but the assumptions and definitions underlying these examples may not be fully resolved, leaving some ambiguity in the proposed approaches.

LikeMath
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Hey!

Is there an infinite ring with exactly two maximal ideals.

Thanks in advance
LiKeMath
 
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What about \mathbb{R}\times\mathbb{R}?
 
micromass said:
What about \mathbb{R}\times\mathbb{R}?
How is multiplication defined here?
 
Erland said:
How is multiplication defined here?

Pointswise: (a,b)\cdot (c,d)=(ac,bd).
 
i didn't check this, but i would try to take a ring and remove a lot of ideals by inverting elements. e.g. take the integers and look at all rational numbers that do not have factors of 2 or 3 in the bottom. then presumably the only maximal ideals left are (2) and (3).

another similar construction, in the ring of all continuous functions on [0,1], invert those that do not vanish at either 0 or 1. Then presumably the only maximal ideals left are those that vanish at one of those points.

I guess this also resembles micromass's example. I.e. take all continuous functions on the 2 point set {0,1} and then you have as maximal ideals the functions that vanish at 0, namely (0,t) and those that vanish at 1, namely (t,0).
 
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