Fully characteristic subgroups

  • Thread starter Thread starter math8
  • Start date Start date
  • Tags Tags
    Characteristic
Click For Summary
SUMMARY

The discussion centers on the group G = Z_2 × S_3, where Z_2 is a cyclic group of order 2 and S_3 is the symmetric group on 3 elements. It is established that the center of G, Z(G), is Z_2 and is not a fully characteristic subgroup of G. The participants emphasize the necessity of demonstrating an endomorphism g from G to G such that g(Z_2) is not contained in Z_2. Additionally, they clarify that every fully characteristic subgroup H is also characteristic, requiring proof that for every automorphism p in Aut(G), p(H) is contained in H, while also addressing the containment of H in p(H).

PREREQUISITES
  • Understanding of group theory concepts, particularly centers and characteristic subgroups.
  • Familiarity with the structure of Z_2 and S_3 groups.
  • Knowledge of endomorphisms and automorphisms in group theory.
  • Basic understanding of invariant subgroups and their properties.
NEXT STEPS
  • Study the properties of endomorphisms in group theory.
  • Learn about the implications of characteristic and fully characteristic subgroups.
  • Explore the structure and properties of the symmetric group S_3.
  • Investigate examples of automorphisms in groups and their effects on subgroups.
USEFUL FOR

Mathematicians, particularly those specializing in group theory, educators teaching abstract algebra, and students seeking to deepen their understanding of subgroup properties and their implications in group structures.

math8
Messages
143
Reaction score
0
Let G=Z_2XS_3 (Z_2:cyclic group of order 2; S_3: Symmetric group on 3) . Show Center of G, Z(G) is not a fully characteristic (or invariant) subgroup of G.

Apparently, Z(G)=Z_2
I know that I need to show that there exists an endomorphism g from G to G such that g(Z_2) is not contained in Z_2.
But I am not sure how.

Also, to prove that every fully characteristic subgroup H is also characteristic, I now how to show that for every automorphism p in Aut(G), p(H) is contained in H, but for some reason I don't see why H is contained in p(H).
 
Physics news on Phys.org
There are subgroups of S_3 that are isomorphic to Z_2. Map the center to one of those. For the second question, p^(-1) is also in Aut(G).
 

Similar threads

  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K