Equivalence Relations and Partitions: Discovering Symmetry and Equivalence in Sets
Equivalence Relations and Partitions: Discovering Symmetry and Equivalence in Sets
Questions
Which of the following is an equivalence relation on the set of integers?
- Congruence modulo 3
- Less than or equal to
- Divisibility by 2
- Remainder when divided by 5
Let R be the relation on the set of real numbers defined by xRy if and only if x - y is an integer. Is R an equivalence relation?
- Yes
- No
Let S be the relation on the set of strings defined by xSy if and only if x and y have the same length. Is S an equivalence relation?
- Yes
- No
Let T be the relation on the set of sets defined by xTy if and only if x and y have the same number of elements. Is T an equivalence relation?
- Yes
- No
What is the partition of the set {1, 2, 3, 4, 5, 6, 7, 8, 9} induced by the equivalence relation of congruence modulo 3?
- {{1, 4, 7}, {2, 5, 8}, {3, 6, 9}}
- {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}
- {{1, 3, 5, 7, 9}, {2, 4, 6, 8}}
- {{1, 2, 4, 5, 7, 8}, {3, 6, 9}}
What is the partition of the set {a, b, c, d, e, f} induced by the equivalence relation of having the same number of sides?
- {{a, b, c}, {d, e, f}}
- {{a, c, e}, {b, d, f}}
- {{a, b, d, e}, {c, f}}
- {{a, c, f}, {b, d, e}}
Let R be an equivalence relation on a set A. Which of the following is true?
- For all x in A, xRx
- For all x and y in A, if xRy then yRx
- For all x, y, and z in A, if xRy and yRz then xRz
- All of the above
Let P be a partition of a set A. Which of the following is true?
- The union of all the sets in P is A
- The intersection of any two sets in P is empty
- Every element of A belongs to exactly one set in P
- All of the above
Which of the following is an example of a partition of the set {1, 2, 3, 4, 5, 6}?
- {{1, 2, 3}, {4, 5, 6}}
- {{1, 3, 5}, {2, 4, 6}}
- {{1, 2}, {3, 4}, {5, 6}}
- {{1, 2, 3, 4}, {5, 6}}
Which of the following is an example of an equivalence relation on the set {1, 2, 3, 4, 5, 6}?
- Congruence modulo 2
- Less than or equal to
- Divisibility by 3
- Remainder when divided by 4
Let R be an equivalence relation on a set A. Which of the following is true?
- The equivalence class of an element x in A is the set of all elements in A that are related to x by R
- The equivalence class of an element x in A is the set of all elements in A that are not related to x by R
- The equivalence class of an element x in A is the set of all elements in A that are equal to x
- None of the above
Let P be a partition of a set A. Which of the following is true?
- Each set in P is an equivalence class of some equivalence relation on A
- The union of all the sets in P is A
- The intersection of any two sets in P is empty
- All of the above
Which of the following is an example of a partition of the set {a, b, c, d, e, f}?
- {{a, b, c}, {d, e, f}}
- {{a, c, e}, {b, d, f}}
- {{a, b}, {c, d}, {e, f}}
- {{a, c, f}, {b, d, e}}
Which of the following is an example of an equivalence relation on the set {a, b, c, d, e, f}?
- Congruence modulo 2
- Less than or equal to
- Divisibility by 3
- Remainder when divided by 4
Let R be an equivalence relation on a set A. Which of the following is true?
- The equivalence class of an element x in A is the set of all elements in A that are related to x by R
- The equivalence class of an element x in A is the set of all elements in A that are not related to x by R
- The equivalence class of an element x in A is the set of all elements in A that are equal to x
- None of the above