Cayley's Theorem (isomorphisms of Cyclics to SN)

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SUMMARY

Cayley's Theorem establishes that any finite group G with order |G| = N is isomorphic to a subgroup of the symmetric group S_N. In the case of the cyclic group C_3, it is isomorphic to the alternating group A_3, as both have matching orders. However, for the cyclic group C_4, the only matching order subgroup in S_4 is the Klein four-group, which is not isomorphic to C_4 due to differing element orders. The discussion highlights the importance of understanding cycle notation and subgroup structures in symmetric groups.

PREREQUISITES
  • Understanding of Cayley's Theorem
  • Familiarity with group theory concepts, particularly cyclic groups
  • Knowledge of symmetric groups and their subgroups
  • Proficiency in cycle notation and permutations
NEXT STEPS
  • Study the properties of symmetric groups, specifically S_3 and S_4
  • Explore the structure and properties of alternating groups, particularly A_3 and A_4
  • Investigate the characteristics of the Klein four-group and its relation to cyclic groups
  • Learn more about group isomorphisms and their implications in abstract algebra
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Students and professionals in mathematics, particularly those focusing on abstract algebra, group theory, and permutation groups.

ChrisVer
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Any finite group G with order |G| = N < \infty is isomorphic (\cong ) to a subgroup of the symmetric group S_N.

I have one question here, let's take the cyclic group of order three: C_3 = \{ e, c, c^2 \}. By Cayley's theorem, this should be isomorphic to some subgroup of S_3.
The subgroups of S_3 are pretty definite, and they are also normal subgroups , created by the union of conjugacy classes. They are the \{ (.) \} , S_3 (both trivial) and the union of \{ (.) \} \cup \{ (...) \} which is the Alternating group A_3.

Is it correct to say then that C_3 \cong A_3 ? the orders seem to match.On the other hand what happens if I go for example to C_4 ? In that case the subgroups of S_4 will be:

1. \{ e \}
2. S_4
3. \{ (.) \} \cup \{ (..)(..) \} \cong C_2 \times C_2
4. \{ (.) \} \cup \{ (...) \} \cup \{ (..)(..) \} \cong A_4

My problem is that in this case, the only "order" which matches is the C_2 \times C_2, But I don't think that the Klein 4-group is isomorphic to the cyclic group, because the orders of the elements don't match. Any help?
 
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are you familiar with cycle notation? isn't (1234) a cycle of order 4, generating a cyclic subgroup of S4 of order 4? e.g. take the subgroup of permutations of the 4 vertices of a square, generated by the rotations of the square about its center, through multiples of 90 degrees.

the problem seems to be with your claim: " In that case the subgroups of S4 will be:..."And you probably meant to post this in the abstract algebra section.
 

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