Unit 2 Flashcards
A blank is a collection of objects
set
The objects in a set are called blank
elements
The blank definition of a set is a list of the elements enclosed in curly braces with the individual elements separated by commas. The following definition of the set A uses roster notation:
A = { 2, 4, 6, 10 }
roster notation
The symbol blank is used to indicate that an element is in a set, as in 2 ∈ A.
∈
The symbol blank indicates that an element is not in a set, as in 5 ∉ A.
∉
The set with no elements is called the blank and is denoted by the symbol ∅
empty set
The empty set is sometimes referred to as the blank and can also be denoted by {}. Because the empty set has no elements, for any element a, a ∉ ∅ is true.
null set
A blank has a finite number of elements.
finite set
An blank has an infinite number of elements.
infinite set
The blank of a finite set A, denoted by |A|, is the number of elements in A.
cardinality
Two sets are blank if they have exactly the same elements
equal
The set of natural numbers: All integers greater than or equal to 0.
N
The set of all integers.
Z
The set of rational numbers: All real numbers that can be expressed as a/b, where a and b are integers and b ≠ 0.
Q
The set of real numbers
R
The superscript blank is used to indicate the positive elements of a particular set. For example, the set R+ is the set of all positive real numbers, and Z+ is the set of all positive integers.
+
The superscript blank is used to indicate the negative elements of a particular set. For example, the set R- is the set of all negative real numbers, and Z- is the set of all negative integers.
-
In blank, a set is defined by specifying that the set includes all elements in a larger set that also satisfy certain conditions. The notation would look like:
A = { x ∈ S : P(x) }
S is the larger set from which the elements in A are taken. P(x) is some condition for membership in A. The colon symbol “:” is read “such that”. The description for A above would read: “all x in S such that P(x)”.
set builder notation
The blank, usually denoted by the variable U, is a set that contains all elements mentioned in a particular context.
universal set
Sets are often represented pictorially with blank. A rectangle is used to denote the universal set U, and oval shapes are used to denote sets within U.
Venn diagrams
If every element in A is also an element of B, then A is a blank of B, denoted as A ⊆ B If there is an element of A that is not an element of B, then A is not a subset of B, denoted as A ⊈ B. If the universal set is U, then for every set A:
∅ ⊆ A ⊆ U
subset
Two sets are blank if and only if each is a subset of the other:
A = B if and only if A ⊆ B and B ⊆ A
equal
If A ⊆ B and there is an element of B that is not an element of A (i.e., A ≠ B), then A is a blank of B, denoted as A ⊂ B.
proper subset
The blank is a subset of every set.
empty set
Every set is a blank of itself.
subset
Set A is a subset of B, denoted blank if every element in A is also in B.
A⊆B
Set A is a proper subset of set B if it is a subset of B and is not equal to B. It is denoted blank
A⊂B
Sets can contain sets as blank.
elements
The cardinality of a set within a set is blank. That is, each set counts as a single element.
1
If S = the set of all sets that are not members of itself, then is S a member of itself?
If S is in S then it cannot be a member of S by definition of being in S.
The blank of a set A, denoted P(A), is the set of all subsets of A. For example, if A = { 1, 2, 3 }, then:
P(A) = { ∅, { 1 }, { 2 }, { 3 }, { 1, 2 }, { 1, 3 }, { 2, 3 }, { 1, 2, 3 } }
power set
Since |A| = 3, the cardinality of the power set of blank
8
Let A be a finite set of cardinality n. Then the cardinality of the power set of blank
A is 2^n, or |P(A)|=2^n.
The power set of a set A is denoted blank
P(A)
The power set of any set A is the set of all blank, including the empty set and A itself.
subsets of A
The blank is an element of every power set.
empty set
The blank of the power set of a set of size n is 2^n
cardinality
Let A and B be sets. The intersection of A and B, denoted blank and read “A intersect B”, is the set of all elements that are elements of both A and B.
A ∩ B
A = { x ∈ Z: x is an integer multiple of 2 }
B = { x ∈ Z: x is an integer multiple of 3 }
A ∩ B = blank
{ x ∈ Z: x is an integer multiple of 6 }
The union of two sets, A and B, denoted blank and read “A union B”, is the set of all elements that are elements of A or B.
A ∪ B
A = { x: student x received an A on midterm 1 }
B = { x: student x received an A on midterm 2 }
Then
A ∪ B = blank
= { x: student x is eligible to skip the final exam }
{ x: student x received an A on midterm 1 or midterm 2 }
The blank of two sets: A∪B
union
The blank of two sets: A∩B
intersection
The union and intersection operations are blank. That is, A∪B=B∪A and A∩B=B∩A
commutative
Set operations can be blank to define even more sets.
combined
The expression A ∩ B ∩ C ∩ D is blank because the order in which intersection operations are applied does not matter.
well-defined
Similarly, the expression A ∪ B ∪ C ∪ D is also blank and defines the set consisting of those elements that are elements of at least one of the four sets: A, B, C, and D.
well-defined
The intersection and union operators can be combined in sequence: A∩(B∪C) or A∪(B∩C). Make sure to complete operations blank first.
inside parentheses
The blank between two sets A and B, denoted A - B, is the set of elements that are in A but not in B.
difference
The difference operation is not blank since it is not necessarily the case that A - B = B - A
commutative
The symmetric difference between two sets, A and B, denoted blank, is the set of elements that are a member of exactly one of A and B, but not both. An alternative definition of the symmetric difference operation is:
A ⊕ B = ( A - B ) ∪ ( B - A )
A ⊕ B
The symmetric difference is blank. A - B = B - A
commutative
The blank of a set A, denoted Ä, is the set of all elements in U that are not elements of A. An alternative definition of Ä is U - A. For example, let U = Z, and define:
A = { x ∈ Z: x is odd }
complement
x ∈ A ∩ B ↔ blank
(x ∈ A) ∧ (x ∈ B)
x ∈ A ∪ B ↔ blank
(x ∈ A) ∨ (x ∈ B)
x ∈ Å ↔ blank
¬(x ∈ A)
x ∈ ∅ ↔ blank
F
x ∈ U ↔ blank
T