Groups of prime order structurally distinct?

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Discussion Overview

The discussion centers on the structural properties of groups of prime order, specifically whether there is only one structurally distinct group (up to isomorphism) for each prime p. Participants explore the implications of the fundamental theorem of finite abelian groups and the nature of isomorphisms between such groups.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asserts that a group G of order p (where p is prime) is isomorphic to Zp and that all its elements are generators, leading to the conclusion that there is only one structurally distinct group of order p.
  • Another participant questions the existence of two groups of order p that are not isomorphic, seeking clarification on the uniqueness of such groups.
  • It is noted that if both groups of order p are isomorphic to Zp, then they must be isomorphic to each other, reinforcing the idea of structural uniqueness.
  • One participant expresses realization about the implications of isomorphism as an equivalence relation in this context.

Areas of Agreement / Disagreement

Participants generally agree that groups of prime order are isomorphic to Zp, but there is uncertainty regarding the existence of non-isomorphic groups of the same order, indicating a lack of consensus on the uniqueness of structurally distinct groups of prime order.

Contextual Notes

The discussion does not resolve the question of whether there are multiple non-isomorphic groups of order p, leaving the matter open for further exploration.

dumbQuestion
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I have a question. If I have a group G of order p where p is prime, I know from the *fundamental theorem of finite abelian groups* that G is isomorphic to Zp (since p is the unique prime factorization of p, and I know this because G is finite order) also I know G is isomorphic to Cp (the pth roots of unity). I also know that G is cyclic and since its isomorphic to Zp I know that all of its elements are generators. Also we know that the only subgroups of G are the trivial subgroup and G itself. We know because G is cyclic, that it is abelian. These are the properties I can determine. [EDIT: Thought of another thing. any nontrivial homomorphism from h: G --> G' should be injective right because ker(h) should be trivial because ker(h) is a subgroup of G and we know G only has subgroups {e} and G itself, and if h is not trivial this means ker(h) must be {e} so its trivial meaning h is injective]But is it true that for each prime p, there is only one structurally distinct group (up to isomorphism)? Is there a theorem that indicates one way or another this fact?EDIT: Think I figured it out. FUndamental theorem of finite abelian groups gauranteeds that if G and G' are both groups of order p where p is prime, then G isomorphic to Zp and G' isomorphic to Zp so this means G isomorphic to G'. Since the selection of G and G' are arbitrary, this means for all G, G' of order p, p prime that G is isomorphic to G' so there is only one structurally distinct group of order p
 
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dumbQuestion said:
But is it true that for each prime p, there is only one structurally distinct group (up to isomorphism)? Is there a theorem that indicates one way or another this fact?

If G is a group of order p, then define f:G → Zp by mapping a generator of G to 1. This produces an isomorphism.
 
But this is showing that G and Zp are isomorphic, right? I'm curious about two groups of order p that are not isomorphic to each other.
 
dumbQuestion said:
But this is showing that G and Zp are isomorphic, right? I'm curious about two groups of order p that are not isomorphic to each other.

Isomorphism is an equivalence relation. If both groups of order p are isomorphic to Zp, then they are isomorphic to each other.
 
Yeah I see that now, I feel kind of stupid now for not seeing it before!
 

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