Is 0 Considered a Prime Element in an Integral Domain?

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Discussion Overview

The discussion revolves around whether 0 can be considered a prime element in an integral domain. Participants explore definitions of prime elements, the implications of these definitions, and the classification of numbers within the context of integral domains.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant asserts that 0 is a prime element because if ab=0 in an integral domain, then either a=0 or b=0, suggesting that the ideal generated by (0) is prime.
  • Another participant counters that 0 is not prime, questioning its classification and suggesting it might be composite instead.
  • A different viewpoint introduces a definition of prime as a number that can only be evenly divided by one and itself, arguing that dividing by zero is undefined, thus excluding 0 from being prime.
  • One participant reflects on the definitions of prime elements, noting that the general definition may contradict traditional definitions that apply to integers, and suggests that 0 could be considered prime in a broader context.
  • Another participant proposes a modified definition of prime that includes the additive inverse, suggesting that 0 might be an "uninteresting prime" since it is never a factor of another number.
  • A participant clarifies the definition of a prime element in a ring, emphasizing that a prime element must be nonzero and nonunit, which leads to the realization that 0 cannot be prime.
  • Discussion includes a classification of ring elements into zero divisors, units, and other elements, with primes being defined as neither units nor zero divisors.

Areas of Agreement / Disagreement

Participants express disagreement regarding the classification of 0 as a prime element. While some argue in favor of its primality based on certain definitions, others firmly reject this notion, leading to an unresolved debate.

Contextual Notes

The discussion highlights the ambiguity in definitions of prime elements across different mathematical contexts, particularly in relation to integral domains and integers. There are unresolved assumptions regarding the applicability of definitions and the implications of classifying 0.

quasar987
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[SOLVED] Is 0 a prime?

Am I missing something or is 0 a prime element in an integral domain?

In the definition of prime element p of an integral domain, we only ask that the ideal generated by p, be prime.

Well (0) is obviously prime because if ab=0 in an integral domain, then it is that a=0 or b=0.
 
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What are the factors of zero?

It might or might not be composite, but it certainly is NOT prime.
 
I don't understand the point you're making.
 
I'm not sure on this but one definition I've heard for a prime is “a number that may only be evenly divided by one and itself.” Zero can be divided by one but dividing by itself would be dividing by zero and hence would be an undefined result.
 
Hi CQ and thanks for your input.

But as far as I can see, this is a definition that makes sense only for integers (and possibly in Euclidean Domains). My point is precisely that the general definition seems to be is in contradiction with this one.

But then again, the general definition claims that -2,-3,-5,... are also primes in Z, while the classical definition considers only positive primes. So it could very well be that 0 is prime in the general setting.

I just wanted to make sure because it surprised me a little to come to this conclusion.
 
Hmm… “a number that may only be evenly divided by one and itself and its additive inverse” then, maybe?

Or alternatively it could simply be that zero is an uninteresting prime because it's never a factor of another number.

MathWorld has http://mathworld.wolfram.com/PrimeNumber.html" on prime numbers, BTW.
 
Last edited by a moderator:
quasar987 said:
Am I missing something or is 0 a prime element in an integral domain?

In the definition of prime element p of an integral domain, we only ask that the ideal generated by p, be prime.

Well (0) is obviously prime because if ab=0 in an integral domain, then it is that a=0 or b=0.

no definitely not, the definition of a prime element b in a ring R , is that b is a nonzero nonunit element s.t. b |ac => b |a or b| c
 
Last edited:
Oh yes, I missed the "nonzero" part in the definition. Funny because I re-read it just before posting too.
 
all ring elements are divided into three classes: zero divisors (including zero), units (including 1), and the other elements.

included among these other elements are the irreducibles, among which are the primes.

in good cases, all irreducibles are prime, and all these other elements are products of primes.

so primes are never units and never zero divisors, and vice versa.
 

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