- #1
johnstobbart
- 22
- 0
I apologize for the repost, but I had no replies to my previous post. I figured that I didn't put down a good enough attempt of a solution. I will try to explain what I did in more detail. I have read the rules for the forum, but if I'm still doing something wrong, please tell me. I want to clear a few things up involving operations with subsets of sets (I'm not sure if this is a more correct term, an example would be Set B below).
U = {1, 2, 3, 4, 5, ∅, {1}},
A = {1, 3}
B = {{1}, 1}
C = {2, 4}
D = {∅, 1, 2}
3 of the questions below are questions that I am asking myself. One of them is an example from a textbook.
We have the following sets:
1. D + B (with + meaning symmetric set difference)
2. B - D (with - meaning set difference)
3. A' (complement of A)
4. Is {∅, {1}} ∈ U? Why?
Number 1:
D + B (with + meaning symmetric set difference)
{∅, 1, 2} + {{1}, 1}
D + B is putting the sets together without combining equal elements.
I am not too sure what to do with the {1}. I'm guessing that {1} and 1 are not the same.
When I perform the operation, I get: {∅, {1}, 2}
Number 2:
B - D (with - meaning set difference)
{{1}, 1} - {∅, 1, 2}
Set difference means that I should remove the like elements that appear in both B and D, and write what is left of B, so I should remove the 1 in set B and the answer will be what is left over.
I think the {1} would stay as there is not another {1} in D.
I get this as the solution:
{{1}}
Number 3:
A' (The complement of A)
The complement of A would be all the elements in the universal set that do not appear in A. I should remove all the elements within A that appear in U and get my answer.
So, I get: {{1}, 2, 4, 5, ∅}
However, to my knowledge, {1} is a subset of U. Can a subset also be an element of a set? I have a feeling that it can't, but I can't put it into words. If my feeling is right however, that would mean that the complement of A' is {2, 4, 5, ∅}.
Number 4:
Is {∅, {1}} ∈ U? Why?
U = {1, 2, 3, 4, 5, ∅, {1}}
I know that ∅ is normally a subset of every set, but because it's included within U, that makes ∅ an element of U. {1} is also included as a part of U, but it is a subset of U. Would that not make it an element as well?
I am guessing that the set {∅, {1}} is not an element of U. To be an element of U, U would have to be represented as: {1, 2, 3, 4, 5, ∅, {1}, {∅. {1}}}
Is that correct?
I have tried my best fleshing out my questions and trying to understand. I hope that someone can help me.
Thank you.
Homework Statement
U = {1, 2, 3, 4, 5, ∅, {1}},
A = {1, 3}
B = {{1}, 1}
C = {2, 4}
D = {∅, 1, 2}
Homework Equations
3 of the questions below are questions that I am asking myself. One of them is an example from a textbook.
We have the following sets:
1. D + B (with + meaning symmetric set difference)
2. B - D (with - meaning set difference)
3. A' (complement of A)
4. Is {∅, {1}} ∈ U? Why?
The Attempt at a Solution
Number 1:
D + B (with + meaning symmetric set difference)
{∅, 1, 2} + {{1}, 1}
D + B is putting the sets together without combining equal elements.
I am not too sure what to do with the {1}. I'm guessing that {1} and 1 are not the same.
When I perform the operation, I get: {∅, {1}, 2}
Number 2:
B - D (with - meaning set difference)
{{1}, 1} - {∅, 1, 2}
Set difference means that I should remove the like elements that appear in both B and D, and write what is left of B, so I should remove the 1 in set B and the answer will be what is left over.
I think the {1} would stay as there is not another {1} in D.
I get this as the solution:
{{1}}
Number 3:
A' (The complement of A)
The complement of A would be all the elements in the universal set that do not appear in A. I should remove all the elements within A that appear in U and get my answer.
So, I get: {{1}, 2, 4, 5, ∅}
However, to my knowledge, {1} is a subset of U. Can a subset also be an element of a set? I have a feeling that it can't, but I can't put it into words. If my feeling is right however, that would mean that the complement of A' is {2, 4, 5, ∅}.
Number 4:
Is {∅, {1}} ∈ U? Why?
U = {1, 2, 3, 4, 5, ∅, {1}}
I know that ∅ is normally a subset of every set, but because it's included within U, that makes ∅ an element of U. {1} is also included as a part of U, but it is a subset of U. Would that not make it an element as well?
I am guessing that the set {∅, {1}} is not an element of U. To be an element of U, U would have to be represented as: {1, 2, 3, 4, 5, ∅, {1}, {∅. {1}}}
Is that correct?
I have tried my best fleshing out my questions and trying to understand. I hope that someone can help me.
Thank you.