Chapter 2.2-2.3 Flashcards

1
Q

Universal Set

A

U, is the set of all elements that are being considered

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2
Q

Complement

A

A’, the set of all elements that are in U and not in A

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3
Q

U’

A

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4
Q

∅’

A

U

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5
Q

(A’)’

A

A

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6
Q

Well-defined

A

a set is well-defined if it is possible to determine whether any given item is or is not an element of the set

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7
Q

Set that is not well-defined

A

{x/x is a nice cat} because nice is ambiguous

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8
Q

Empty set or null set

A

is the set with no elements, denoted ∅

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9
Q

Finite

A

a set is finite if the number of elements in the set is a whole number

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10
Q

cardinal number or cardinality

A

the cardinality of a finite set A, denoted n(A), is the number of elements in A

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11
Q

Cardinality of the empty set

A

0

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12
Q

Set A is equal to set B if….

A

if and only if, A and B have exactly the same elements, denoted A=B

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13
Q

Set A is equivalent to set B if…

A

if and only if the cardinality of A, n(A), equals the cardinality of B, n(B), denoted A~B

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14
Q

Subset

A

Let A and B be two sets. A is a subset of B, denoted A ⊆ B if and only if every element of A is also in B
A= {1, 2, 3}
B= {1, 2, 3, 4, 5}

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15
Q

Proper Subset

A

Let A and B be sets, A is a proper subset of B, denoted A⊂B, if and only if A ⊆ B and A≠B
A= {1, 2, 3}
B= {1, 2, 3, 4, 5}

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16
Q

Is this a subset?
A= {5, 10, 44}
B= {5, 10, 44}

17
Q

Is this a subset?

W⊆ ℕ

18
Q

Is this a subset?

A’⊆A

19
Q

Is this a proper subset?
A= {5, 10, 44}
B= {5, 10, 44}

A

No, because A=B

20
Q

How to find number of subsets

A

If n(A)=K then A has 2^K subsets

21
Q

How to find the number of proper subsets

A

If n(A)=K then A has 2^K - 1 proper subsets

22
Q

Intersection

A

Let A and B be two sets, the intersection of A and B, denoted A∩ B, is the set of all elements that belong to both A and B
A∩ B= {x/xEA and xEB}

23
Q
U= {1, 2, 3...10}
A= {1, 4, 5, 7}
B= {2, 3, 5, 10}
C= {3, 8, 10}
Find A∩ B
24
Q
U= {1, 2, 3...10}
A= {1, 4, 5, 7}
B= {2, 3, 5, 10}
C= {3, 8, 10}
Find B∩ C
25
``` U= {1, 2, 3...10} A= {1, 4, 5, 7} B= {2, 3, 5, 10} C= {3, 8, 10} Find A∩ C ```
∅, A and C are disjoint
26
Union
let A and B be sets, the union of A and B, denoted AUB, is the set of all elements that belong to either A or B AUB={x/xEA or xEB}
27
``` U= {1, 2, 3...10} A= {1, 4, 5, 7} B= {2, 3, 5, 10} C= {3, 8, 10} Find A U B ```
{1, 2, 3, 4, 5, 7, 10}
28
``` U= {1, 2, 3...10} A= {1, 4, 5, 7} B= {2, 3, 5, 10} C= {3, 8, 10} Find A U C ```
{ 1, 3, 4, 5, 7, 8, 10}
29
``` U= {1, 2, 3...10} A= {1, 4, 5, 7} B= {2, 3, 5, 10} C= {3, 8, 10} Find B U C ```
{2, 3, 5, 8, 10}
30
A U ∅
A
31
``` U= {1, 2, 3, 4...10} A= {2, 4, 6, 8} B= {3, 6, 9} C= {1, 4, 8} Find A U (B ∩ C) ```
{2, 4, 6, 8}
32
``` U= {1, 2, 3, 4...10} A= {2, 4, 6, 8} B= {3, 6, 9} C= {1, 4, 8} Find B ∩ C' ```
{3, 6, 9}
33
``` U= {1, 2, 3, 4...10} A= {2, 4, 6, 8} B= {3, 6, 9} C= {1, 4, 8} Find [A ∩ (B U C)]' ```
B U C= {1, 3, 4, 6, 8, 9} A ∩ (B U C) = {4, 6, 8} [A ∩ (B U C)]' = {1, 2, 3, 5, 7, 9, 10}
34
DeMorgan's Laws
For all sets A and B: (A U B)' = A' ∩ B' (A ∩ B)' = A' U B'
35
Commutative Property
A U B = B U A | A ∩ B = B ∩ A
36
Associative Property
``` A ∩ (B ∩ C) = (A ∩ B) ∩ C A U (B U C) = (A U B) U C ```
37
Distributive Property
``` A ∩ (B U C) = (A ∩ B) U (A ∩ C) A U (B ∩ C) = (A U B) ∩ (A U C) ```