Find the elementary divisors and invariant factors

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SUMMARY

The discussion focuses on finding the elementary divisors and invariant factors of two groups: \( G_1 = \mathbb{Z}_6 \times \mathbb{Z}_{12} \times \mathbb{Z}_{18} \) and \( G_2 = \mathbb{Z}_{10} \times \mathbb{Z}_{20} \times \mathbb{Z}_{30} \times \mathbb{Z}_{40} \). For \( G_1 \), the elementary divisors identified are \( \{2, 3, 2^2, 3, 2, 3^2\} \). For \( G_2 \), the elementary divisors are \( \{5, 2, 2^2, 5, 2, 3, 5, 2^3, 5\} \). The next step involves applying the Chinese remainder theorem to split each factor into cyclic primary-p groups and regrouping them to find the invariant factors.

PREREQUISITES
  • Understanding of group theory concepts, specifically elementary divisors and invariant factors.
  • Familiarity with the structure of cyclic groups and direct products of groups.
  • Knowledge of the Chinese remainder theorem and its application in group theory.
  • Basic skills in prime factorization and decomposition of integers.
NEXT STEPS
  • Study the application of the Chinese remainder theorem in group theory.
  • Learn how to compute invariant factors for direct products of cyclic groups.
  • Explore the classification of finite abelian groups and their structure.
  • Review examples of elementary divisors and invariant factors in various group contexts.
USEFUL FOR

This discussion is beneficial for students and professionals in mathematics, particularly those studying abstract algebra, group theory, and anyone looking to deepen their understanding of finite abelian groups and their properties.

fabiancillo
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Hello I have problems with this exercise

Find the elementary divisors and invariant factors of each of the following groups

a) $G1= Z_6 \times Z_{12} \times Z_{18}$ , b) $G_2= Z_{10} \times Z_{20} \times Z_{30} \times Z_{40}$Thanks
 
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a) I think that elementary divisors are $\{2,3,2^2,3,2,3^2 \} $ because is the prime decomposition of ${6,12,18}$.

b) elementary divisors are $\{5 ,2 ,2^2, 5, 2, 3, 5, 2^3, 5 \}$
. But I don't use the Chinese remainder theorem to split each factor into cyclic pp-groups, then regroup
 
Last edited:
You are correct so far in parts (a) and (b). You just need to find the invariant factors now.
 

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