问题


There is a single choice question about abstract algebra. Answer the question by replying A, B, C or D.
Question: Statement 1 | If K is a nonzero subgroup of a finitely generated free abelian group, then K is free abelian. Statement 2 | If K is a nonzero subgroup of a finitely generated free abelian group, then G / K is free abelian.
A. True, True
B. False, False
C. True, False
D. False, True
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0

C. True, False.

Reasoning Skill: Consequence Evaluation

This question requires the test-taker to evaluate the consequences of a subgroup being part of a finitely generated free abelian group. The correct answer, C. True, False, indicates that the test-taker understands that a nonzero subgroup of a finitely generated free abelian group is indeed free abelian (Statement 1 is true), but the quotient group G / K is not necessarily free abelian (Statement 2 is false). This requires the ability to analyze the properties of subgroups and quotient groups in abstract algebra and evaluate the consequences of these properties.

Note: The question is designed to test the understanding of the fundamental theorem of finitely generated abelian groups, which states that every finitely generated abelian group is isomorphic to a direct sum of cyclic groups. The correct answer requires the application of this theorem to determine the properties of subgroups and quotient groups.
C
deepseekr1

The first statement is true because subgroups of finitely generated free abelian groups are also free abelian, as they inherit the structure without torsion. The second statement is false because taking a quotient by a nontrivial subgroup can introduce torsion (e.g., ℤ/2ℤ from ℤ/2ℤ), making the quotient not free abelian.

Answer: C
C
gpto1 C C
GPT-4o C. True, False

Statement 1 is true: If \( K \) is a nonzero subgroup of a finitely generated free abelian group, then \( K \) is indeed free abelian.

Statement 2 is false: If \( K \) is a nonzero subgroup of a finitely generated free abelian group \( G \), it is not necessarily true that \( G / K \) is free abelian.
C
llama3.1-70B-Instruct

Statement 1 is true. Statement 2 is false.
C
llama3.1-405B-Instruct

C
C
DeepSeek-Coder-V2 C. True, False C
Qwen2-72B-Instruct C. True, False C
baichuan4 D. False, True C
doubao C

Statement 1 is true. A nonzero subgroup of a finitely generated free abelian group is indeed free abelian.

However, Statement 2 is false. Just because K is a subgroup of a finitely generated free abelian group, it does not necessarily mean that the quotient group G / K is free abelian.
C
minimax C. True, False

Statement 1 is true because any subgroup of a free abelian group is free abelian. This is a consequence of the fundamental theorem of finitely generated abelian groups, which states that every finitely generated abelian group G can be expressed as a direct sum of cyclic subgroups of prime power order. When you take a subgroup K of such a group, it will also be a direct sum of cyclic groups, and hence free abelian.

Statement 2 is false because the quotient of a free abelian group by a subgroup does not necessarily have to be free abelian. The quotient group G / K can be free abelian only if K is a direct summand of G, which is not guaranteed by the information given in the statement.
C
kimi C. True, False

Statement 1 is true because a subgroup of a free abelian group is also free abelian. This is a well-known result in group theory.

Statement 2 is false because the quotient group G / K of a finitely generated free abelian group G by a nonzero subgroup K is not necessarily free abelian. The structure of the quotient group can be quite complex and depends on the specific properties of K within G.
C
wenxinyiyan C C
zhipu C. True, False

Explanation:
- Statement 1 is true because a nonzero subgroup of a finitely generated free abelian group is indeed free abelian. This follows from the structure theorem for finitely generated abelian groups.
- Statement 2 is false because the quotient of a finitely generated free abelian group by a nonzero subgroup is not necessarily free abelian. The quotient group might have torsion elements, which would prevent it from being free abelian. For instance, consider \(\mathbb{Z} \times \mathbb{Z} / \langle (2, 0) \rangle\), which is isomorphic to \(\mathbb{Z} \times \mathbb{Z}_2\), which is not free abelian.
C
gpto1 C C
deepseekv3 The correct answer is:

**C. True, False**

### Explanation:
1. **Statement 1**: If \( K \) is a nonzero subgroup of a finitely generated free abelian group, then \( K \) is free abelian.
- This is **true**. By the structure theorem for finitely generated abelian groups, every subgroup of a finitely generated free abelian group is also free abelian.

2. **Statement 2**: If \( K \) is a nonzero subgroup of a finitely generated free abelian group, then \( G / K \) is free abelian.
- This is **false**. The quotient group \( G / K \) may have torsion elements and thus may not be free abelian. For example, if \( G = \mathbb{Z} \) and \( K = 2\mathbb{Z} \), then \( G / K \cong \mathbb{Z}/2\mathbb{Z} \), which is not free abelian.

Thus, the correct choice is **C. True, False**.
C