Exercise · ZW-CLASSIFICATION-OF-FINITE-ABELIAN-GROUPS-001 · ★☆☆ Basic
How many abelian groups of order \(12\) are there, up to isomorphism?
Choose one option.
Show answer
- B. 2
Explanation
Since \(12=2^2\cdot3\), the part of order \(4\) is either \(\mathbb{Z}_4\) or \(\mathbb{Z}_2\times\mathbb{Z}_2\) and the part of order \(3\) is unique: there are 2 groups.
Review the concept: Classification of finite abelian groups
Every finite abelian group \(G\) is isomorphic to a direct product of cyclic groups \(\mathbb{Z}_{p^k}\), with \(p\) prime and \(k\ge1\), unique up to order.
\[G\cong\mathbb{Z}_{p_1^{k_1}}\times\cdots\times\mathbb{Z}_{p_r^{k_r}}\]
More practice problems: classification of finite abelian groups
- ZW-CLASSIFICATION-OF-FINITE-ABELIAN-GROUPS-002 How many abelian groups of order 16 are there, up to isomorphism?
- ZW-CLASSIFICATION-OF-FINITE-ABELIAN-GROUPS-003 Which of these groups is isomorphic to ℤ_12?
- ZW-CLASSIFICATION-OF-FINITE-ABELIAN-GROUPS-004 Decompose ℤ_6×ℤ_10 into cyclic factors of prime-power order.
- ZW-CLASSIFICATION-OF-FINITE-ABELIAN-GROUPS-005 How many abelian groups of order 35 are there, up to isomorphism?
- ZW-CLASSIFICATION-OF-FINITE-ABELIAN-GROUPS-006 What is the largest order of an element of ℤ_4×ℤ_6?
- ZW-CLASSIFICATION-OF-FINITE-ABELIAN-GROUPS-007 How many abelian groups of order 72 are there, up to isomorphism?
- ZW-CLASSIFICATION-OF-FINITE-ABELIAN-GROUPS-008 Which pair of groups is isomorphic?
- ZW-CLASSIFICATION-OF-FINITE-ABELIAN-GROUPS-009 How many elements of order 2 does ℤ_2×ℤ_2×ℤ_4 have?