MATH255 - Mid Term Exam Flashcards

(126 cards)

1
Q

What is a statement

A

An expression that is either true or false, without ambiguity.Example: “I am a man”

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2
Q

What is a True Statement

A

Definition: A logically valid statement that is true.Example: “3 + 4 = 7”

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3
Q

What is a Not Statement

A

Definition: A statement negated using the “~” symbol.Example: “~(3 + 4 = 7)”

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4
Q

What is Ambiguity

A

Definition: Lack of clarity or uncertainty in a statement.Example: “x > 2” (ambiguous because it depends on the value of x)

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5
Q

What is There exists

A

Definition: Indicates the existence of at least one element satisfying a condition.Example: “There exists x such that x < 2”

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6
Q

What is a False Statement

A

Definition: A logically invalid statement that is false.Example: “If x^2 = 9, then x = 1 or x = -1”

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7
Q

What is a Conjunction

A

Definition: A logical operation that combines two statements into a single statement, true only if both original statements are true.Example: “It is raining outside” ^ “I am wearing a raincoat”p ^ q “and”

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8
Q

What is a Disjunction

A

Definition: A logical operation that combines two statements into a single statement, true if at least one of the original statements is true.Example: “I take the bus to school” v “I take the train to school”p v q “or”

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9
Q

What is a Conditional

A

Definition: A statement that implies that if one condition is met, another condition must also be met.Example: “If I work hard, then I do well.”p > q “implies”

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10
Q

What is a Tautology

A

Definition: A compound statement that is always true, regardless of the truth values of its components.Example: “p v ~p”

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11
Q

What is a Fallacy

A

Definition: A compound statement that is always false, regardless of the truth values of its components.Example: “p ^ ~p”

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12
Q

What is a Biconditional

A

Definition: A statement that implies two conditions are equivalent.Example: “x^3 = -8” <-> “x = -2”p <-> q “p implies q, but also q implies p”

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13
Q

What is Equivalence Laws

A

Definition: A set of logical laws that describe how logical operators interact with each other.Example: Commutative, Associative, Distributive, etc.

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14
Q

What is a Contingency

A

Definition: A statement that is sometimes true and sometimes false, neither a tautology nor a fallacy.Example: “p ^ q”

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15
Q

What is Equivalence

A

Definition: Two statements are logically equivalent if they have identical truth table values.Example: “p ≡ ~(~p)”

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16
Q

What is Substitution Rule

A

Definition: If in a tautology all instances of a variable are replaced by the same statement, it remains a tautology.Example: p^~p turns into q^~q

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17
Q

What is Distributive Laws

A

Definition: Laws stating how one operation distributes over another.Example: p ∨ (q ∧ r) ≡ (p ∨ q) ∧ (p ∨ r)

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18
Q

What is Associative Laws

A

Definition: Laws stating that the grouping of operands does not change the result.Example: (p ∨ q) ∨ r ≡ p ∨ (q ∨ r)

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19
Q

What is Commutative Laws

A

Definition: Laws stating that the order of operands does not change the result.Example: p ∨ q ≡ q ∨ p

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20
Q

What is Double Negation Law

A

Definition: The negation of a negated statement.Example: ∼∼ p ≡ p

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21
Q

What is De Morgan’s Laws

A

Definition: Laws describing how negation distributes over logical operators.Example: ∼(p ∨ q) ≡ ∼p ∧ ∼q

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22
Q

What is Implication Laws

A

Definition: Laws relating to conditional statements.Example: p ↔ q ≡ (p → q) ∧ (q → p)

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23
Q

What is Main Connective

A

Definition: The primary logical operator in a compound statement that binds it together.Example: In (p ∨ q) → (r ∧ s), “→” is the main connective.

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24
Q

What is Universal Quantifier

A

Definition: Symbolized as ∀, it means “For all.” Used in predicate logic to denote that a statement applies to all elements in a given domain.Example: ∀x ∈ D, p(x) means “For all x in the domain D, p(x) is true.”

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25
What is Existential Quantifier
Definition: Symbolized as ∃, it means "There exists." Used in predicate logic to indicate that there is at least one element in a given domain for which a statement is true.Example: ∃x ∈ D, p(x) means "There exists an x in the domain D for which p(x) is true."
26
What is Predicate
Definition: A variable statement that evaluates to true or false when specific values are substituted for its variables.Example: p(x): "x is an integer less than 5"
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What is Universal Quantifier Example
Definition: An example illustrating the use of the universal quantifier (∀) in a statement.Example: ∀x ∈ D, p(x) means "For all x in the domain D, p(x) is true."
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What is Domain
Definition: The set of all possible values that can be substituted into a predicate.Example: Domain of p is Z (the set of all whole numbers).
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What is Truth Set
Definition: A subset of the domain that contains the elements for which the predicate is true.Example: Truth set of p(x) contains {-2, -1, 0, 1, 2, 3, 4}.
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What is Existential Quantifier Example
Definition: An example demonstrating the use of the existential quantifier (∃) in a statement.Example: ∃x ∈ D, p(x) means "There exists an x in the domain D for which p(x) is true."
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What is Negation of Existential Statement
Definition: The process of negating an existential statement to make it a universal statement.Example: ~∃x ∈ Z, x is even becomes ∀x ∈ Z, x is not even.
32
What is Negation of Universal Statement
Definition: The process of negating a universal statement to make it an existential statement.Example: ~∀x ∈ R, x > 0 becomes ∃x ∈ R, x ≤ 0.
33
What is Direct Proof
Definition: A method of proof that starts with given assumptions and progresses in a forward manner to reach a conclusion.Example: Proving that if 3x - 9 = 15, then x = 8.
34
What is Modus Ponens
Definition: A valid form of argument where if you have a conditional statement "If p, then q" and you know p is true, you can conclude that q is true.Example: If p, then q; p; ∴ q.
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What is Proof by Contradiction
Definition: A proof technique that assumes the opposite of what needs to be proved, and then shows that this assumption leads to a contradiction, thus establishing the original statement's truth.Example: Proving that for all n ∈ N, if n^2 is even, then n is even, by contradiction.
36
What is Modus Ponens Example
Definition: An example illustrating the use of Modus Ponens in a logical argument.Example: If it's raining (p), then I will bring an umbrella (q); It's raining (p); ∴ I will bring an umbrella (q).
37
What is Law of Syllogism
Definition: A valid form of argument where if you have two conditional statements "If p, then q" and "If q, then r," you can conclude "If p, then r."Example: If p, then q; If q, then r; ∴ If p, then r.
38
Law of Syllogism Example
Definition: An example illustrating the use of the Law of Syllogism in a logical argument.Example: If I study (p), I will pass the exam (q); If I pass the exam (q), I will graduate (r); ∴ If I study (p), I will graduate (r).
39
What is Law of Contrapositive
Definition: A valid form of argument that states if you have a conditional statement "If p, then q," the contrapositive statement "If ~q, then ~p" is also true.Example: If p, then q; ∴ If ~q, then ~p.
40
What is Law of Contrapositive Example
Definition: An example demonstrating the use of the Law of Contrapositive in a logical argument.Example: If it's a square (p), then it has four sides (q); ∴ If it doesn't have four sides (~q), then it's not a square (~p).
41
What is Negation mean
~
42
What is Conjunction mean
^
43
What is Disjunction mean
v
44
What is Conditional mean
->
45
What is Biconditional mean
<->
46
What is ~
Negation
47
What is ^
Conjunction
48
What is v
DIsjunction
49
What is ->
Conditional
50
What is <->
Biconditional
51
What is the truth table for Negation
P ~PT FF T
52
What is Proof by Contradiction
It is taking the statement and proving it is true/false by attempting to make it the opposite (false/true) and depends if it is possible or not
53
What is the truth table for Disjunction
p q pvqT T FT F TF T TF F F
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What is the truth table for Conjunction
p q p^qT T TT F FF T FF F F
55
What is the rule for remembering Bi-Conditional truth table values
TT and FF = True but TF and FT are False
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What is the truth table for Conditional
p q p>qT T TT F FF T TF F T
57
What is the rule for remembering Conditional truth table values
p implies q is true in all cases except for true implies false (TF = False)
58
What is ∀
Universal Quantifier - "For All"
59
What is the truth table for Bi-Conditional
p q p>qT T TT F FF T FF F T
60
What is ∃
There Exists/Is
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What is ∈
Set of / in a set of
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What is Z
All/every WHOLE number
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What is /∈
Element is not in a set of
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What is R
Every real number/every imaginable number
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What is ∴
Therefore
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What is Z++
Every whole positive number
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What is N
Natural number - Positive whole number
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What is Ø
Empty set
69
What is A ⊆ B
A is a subset of B
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What is ≠
Not equal to
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What is ≤
Less than or equal to
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What is A∪B
A UNION B
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What is A∩B
A INTERSECTION B
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What is Ā or A’
Complement of A
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What is |S|
Cardinality |S| = n and say S has cardinality n (number of elements is n) Note: |∅| = 0
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What is Z \ A
The \ means without so here it is Z without A, aka the Difference
77
Does Order in Sets matter?
In set theory, order is not important. For example, {1, 3} is the same as {3, 1}. Sets are unordered collections of elements.
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What is with Repeats in Sets
Repetition of elements in a set is not relevant. For example, {1, 3} is the same as {3, 3, 1, 3, 1, 1, 3}. Sets do not count repetitions; they only consider distinct elements.
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What is Finite Set
A set that contains a finite (limited) number of elements.
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What is Infinite Set
A set that contains an infinite (unlimited) number of elements.
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What is Natural Numbers (N)
The set of natural numbers consists of all positive whole numbers, including zero (0, 1, 2, 3, ...).
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What is Universe (U)
In set theory, the universe (U) is a concept used to define the context or scope for sets. It represents the set of all elements relevant to a particular problem.
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What is Integers (Z)
The set of integers includes all whole numbers, both positive and negative, as well as zero (-3, -2, -1, 0, 1, 2, 3, ...).
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What is Rational Numbers (Q)
The set of rational numbers consists of all numbers that can be expressed as the quotient or ratio of two integers. For example, fractions like 1/2 or -3/4 are rational numbers.
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What is Q
Rational Numbers
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What is Set Notation
The use of curly braces, such as { ... }, is used to denote sets. For example, {1, 2, 3} represents a set with the elements 1, 2, and 3.
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What is Empty Set (∅)
The empty set is a set with no elements. It is denoted as ∅ or {} and is used to represent a set with no satisfying elements.
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What is Subset (⊆)
Set A is a subset of set B (A ⊆ B) if every element of A is also in B.
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What is Cardinality of a Set
The cardinality of a set is the number of elements it contains. It is denoted as |S|.
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What is Superset
If A is a subset of B, then B is a superset of A.
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What is Identity Element
An identity element is an element that, when combined with another element using a specific operation, leaves the other element unchanged. For example, 0 is the additive identity, and 1 is the multiplicative identity.e * x = x
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What is Inverse Element
An element's inverse is the value that, when combined with the original element using a specific operation, results in the identity element.x * y = e
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What is Commutative
An operation is commutative if the order of the operands does not affect the result. For example, addition and multiplication are commutative operations.
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What is Associative
An operation is associative if the grouping of operands does not affect the result. For example, addition and multiplication are associative operations.
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What is Well-Ordered Set
A set is well-ordered if every nonempty subset of the set has at least one smallest element.
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What is Distributive
An operation is distributive if it distributes over another operation. For example, multiplication is distributive over addition.
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What is Intersection (∩)
The intersection of sets A and B (A ∩ B) is the set containing all elements that are in both A and B.
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What is Union (∪)
The union of sets A and B (A ∪ B) is the set containing all elements that are in either A or B.
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What is Set Difference (B - A or B\A)
The set difference B - A (or B\A) contains all elements that are in B but not in A.
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What is Complement (Ā or A')
The complement of set A (Ā or A') contains all elements that are not in A with respect to the universe U.
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What is the difference between a ( and [ in sets
‘(‘ means the -2 is not included/counted‘]’ means the 5 is included/counted
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What does (2, 5] mean
All the numbers between 2 and 5 but not counting 2
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{1} ∈ {x ∈ N : x^2 = 1}is this true or false
False as the Universe is Natural numbers and given is a set not N
104
What is Cardinality of an empty set
0
105
{0,2} ⊆ {1,2,3}True or false
False as 0 is not in set 2
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{1,2} ⊆ {1,2,3}True/False?
True as all of A is in B
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What is a subset
A subset is a set A derived from set B such that every element of set A is in set B
108
What is a graph in graph theory?
A graph consists of a pair of finite sets: a nonempty set of vertices (V) and a set of edges (E), where each edge is associated with a subset of V containing 1 or 2 vertices.
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What is a loop in a graph?
A loop is an edge with only one endpoint, essentially a connection from a vertex to itself in a graph.It counts as two edges to its own vertex
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What are parallel edges in a graph?
Parallel edges are two or more edges that share the same endpoint(s) in a graph.
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What is a simple graph?
A simple graph is a graph that does not contain loops or parallel edges.
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What is the definition of adjacent vertices in a graph?
Two vertices in a graph are considered adjacent if they are connected by an edge.
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What is a subgraph in graph theory?
A graph H is a subgraph of a graph G if every vertex and edge in H is also present in G, and the edges in H have the same endpoints as in G.
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What is a complete graph?
A complete graph, denoted as K^n, is a simple graph with n vertices where every pair of distinct vertices is connected by an edge.
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What is a bipartite graph?
A bipartite graph is a simple graph that can be divided into two sets of vertices (U and W) such that all edges connect a vertex from set U to a vertex in set W.
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What is a complete bipartite graph?
A complete bipartite graph, denoted as Km,n, is a simple graph with two sets of vertices {v1, … , vm} and {w1, … , wn}, where there is an edge from each vi to each wj, and no edges within either set.
117
How is the degree of a vertex defined in a graph?
The degree of a vertex v, denoted as δ(v), is the number of edges incident on v, counting loops twice.
118
Define the degree of a graph.
The degree of a graph is the maximum degree among all its vertices.
119
Define the degree of a vertex.
The amount of edges connecting to it
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What does the Handshake Theorem state
The Handshake Theorem states that the degree of a graph is equal to twice the number of its edges.
121
What is a tree in graph theory?
A tree is a connected graph that has no simple circuits (loops) or loops.
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What is a spanning tree in a graph?
A spanning tree of a graph is a subgraph that includes every vertex of the original graph and is itself a tree.
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Do all connected graphs have spanning trees?
Yes, every connected graph has at least one spanning tree.
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What is a weighted graph?
A weighted graph is a graph in which each edge has an associated positive weight.
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How does Prim's Algorithm build a minimum spanning tree?
Prim's Algorithm builds a minimum spanning tree by selecting a vertex and expanding outward, adding one edge and one vertex at each step.
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How does Kruskal's Algorithm find a minimum spanning tree?
Kruskal's Algorithm finds a minimum spanning tree by examining edges in increasing weight order and adding edges that do not create circuits.