问题


There is a single choice question about abstract algebra. Answer the question by replying A, B, C or D.
Question: Which of the following statements is true?
A. Every equivalence relation is a partial-ordering relation.
B. Number of relations form A = {x, y, z} to B= (1, 2), is 64.
C. Empty relation _ is reflexive
D. Properties of a relation being symmetric and being un-symmetric are negative of each other.
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0

B
B
deepseekr1

The correct answer is **B**.

**Analysis of each option:**

- **A**: Equivalence relations require symmetry, while partial orders require antisymmetry. These are conflicting properties, making A false.
- **B**: The number of relations from \( A = \{x, y, z\} \) to \( B = \{1, 2\} \) is calculated as \( 2^{|A \times B|} = 2^{3 \times 2} = 2^6 = 64 \). Thus, B is true.
- **C**: Reflexivity requires every element to relate to itself. The empty relation on a non-empty set lacks these pairs, so C is false.
- **D**: Symmetric and antisymmetric are not logical negations (e.g., a relation can be neither or both). Hence, D is false.

**Answer: B**
B
gpto1 B B
GPT-4o Answer: D B
llama3.1-70B-Instruct

B
B
llama3.1-405B-Instruct

B
B
DeepSeek-Coder-V2 B B
Qwen2-72B-Instruct B. Number of relations form A = {x, y, z} to B= (1, 2), is 64. B
baichuan4 D B
doubao D

A is incorrect as an equivalence relation is not necessarily a partial-ordering relation. B is incorrect as the number of relations from A to B is 2^(3*2) = 2^6 = 64. C is incorrect as the empty relation is not reflexive. D is correct as a relation cannot be both symmetric and un-symmetric simultaneously.
B
minimax B. Number of relations from A = {x, y, z} to B = {1, 2}, is 64.

Explanation:
The number of relations from a set A with m elements to a set B with n elements is 2^(m*n). In this case, A has 3 elements and B has 2 elements, so the number of relations is 2^(3*2) = 2^6 = 64.

The other options are false for the following reasons:
A. An equivalence relation is reflexive, symmetric, and transitive, but a partial-ordering relation requires antisymmetry in addition to reflexivity and transitivity.
C. The empty relation is not reflexive because there are no elements that relate to themselves.
D. A relation being symmetric means if a is related to b, then b is related to a. Being unsymmetric does not mean the opposite; it means that there exists at least one pair (a, b) such that a is related to b but b is not related to a. These are not simply negatives of each other.
B
kimi D. Properties of a relation being symmetric and being un-symmetric are negative of each other.

Let's analyze each option:

A. This statement is false. An equivalence relation is not necessarily a partial-ordering relation. Equivalence relations are used to partition a set into disjoint equivalence classes, whereas partial orders are used to define a ranking or ordering of elements.

B. This statement is false. The number of relations from a set A to a set B is 2^(|A|*|B|), where |A| and |B| are the cardinalities of sets A and B, respectively. In this case, |A| = 3 and |B| = 2, so the number of relations is 2^(3*2) = 2^6 = 64. However, the question seems to be asking for the number of relations from A to B, not the number of functions, which is a different concept.

C. This statement is false. An empty relation is not reflexive because a reflexive relation requires that every element in the set be related to itself, and in an empty relation, there are no pairs at all.

D. This statement is true. A relation is symmetric if for every pair (a, b) in the relation, (b, a) is also in the relation. A relation is antisymmetric (or un-symmetric) if for every pair (a, b) in the relation, (b, a) cannot be in the relation unless a = b. These properties are indeed opposites of each other.
B
wenxinyiyan D

Explanation:
A. Every equivalence relation is reflexive, symmetric, and transitive. However, a partial-ordering relation is reflexive, antisymmetric (which is not the same as symmetric), and transitive. Therefore, not every equivalence relation is a partial-ordering relation. So A is false.

B. The number of relations from A to B is given by $2^{|A| \times |B|}$. Here, $|A| = 3$ and $|B| = 2$. So the number of relations is $2^{3 \times 2} = 2^6 = 64$. However, the question states B as a set with parentheses instead of curly braces, which typically indicates an ordered pair rather than a set. If we consider B as an ordered pair, then the statement is false. Assuming this was a typo and B is meant to be a set, then B is true. But since the original statement uses parentheses, we consider B as false.

C. An empty relation is not reflexive because reflexivity requires that every element of the set be related to itself, which is not the case in an empty relation. So C is false.

D. A relation is symmetric if $(a, b)$ being in the relation implies $(b, a)$ is also in the relation. A relation is antisymmetric if $(a, b)$ and $(b, a)$ being in the relation implies $a = b$. A relation is un-symmetric (or asymmetric) if it is not symmetric, i.e., there exists at least one pair $(a, b)$ such that $(a, b)$ is in the relation but $(b, a)$ is not. Thus, being symmetric and being un-symmetric are mutually exclusive properties of a relation, making them negatives of each other. So D is true.
B
zhipu C

Explanation:
- A. Every equivalence relation is a partial-ordering relation. This is false. An equivalence relation is reflexive, symmetric, and transitive, whereas a partial-ordering relation is reflexive, antisymmetric, and transitive. The properties of symmetry and antisymmetry are different, so not every equivalence relation is a partial-ordering relation.
- B. Number of relations from A = {x, y, z} to B = {1, 2} is 64. This is false. The number of relations from a set A to a set B is \(2^{|A| \times |B|}\). Here, \(|A| = 3\) and \(|B| = 2\), so the number of relations is \(2^{3 \times 2} = 2^6 = 64\), but since B is written as (1, 2) which is typically not how sets are denoted, this could be interpreted as a mistake.
- C. Empty relation is reflexive. This is true. An empty relation on any set is reflexive because there are no elements to violate the reflexive property (which states that every element is related to itself).
- D. Properties of a relation being symmetric and being unsymmetric are negative of each other. This is false. Being symmetric and being unsymmetric are not negatives of each other. A relation can be neither symmetric nor unsymmetric, or it can be both if it is empty or trivial.

So, the correct answer is C.
B
gpto1 B B
deepseekv3 The correct answer is **B**.

### Explanation:
- **A. Every equivalence relation is a partial-ordering relation.**
This is false. An equivalence relation is reflexive, symmetric, and transitive, while a partial-ordering relation is reflexive, antisymmetric, and transitive. Symmetry and antisymmetry are not compatible.

- **B. Number of relations from A = {x, y, z} to B = {1, 2}, is 64.**
This is true. The number of possible relations from set A to set B is \( 2^{|A| \times |B|} \). Here, \( |A| = 3 \) and \( |B| = 2 \), so the number of relations is \( 2^{3 \times 2} = 2^6 = 64 \).

- **C. Empty relation is reflexive.**
This is false. A relation is reflexive if every element is related to itself. The empty relation does not satisfy this condition unless the set itself is empty.

- **D. Properties of a relation being symmetric and being un-symmetric are negative of each other.**
This is false. A relation can be neither symmetric nor antisymmetric, so these properties are not strict negatives of each other.

Thus, the correct answer is **B**.
B