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Questions and Answers
The intersection of a family of sets (Ai)i∈I is denoted by "______"
The intersection of a family of sets (Ai)i∈I is denoted by "______"
∩i∈I Ai
The union of a family of sets (Ai)i∈I includes all elements that belong to at least one set in the family.
The union of a family of sets (Ai)i∈I includes all elements that belong to at least one set in the family.
True (A)
What is the difference between the intersection and the union of a family of sets?
What is the difference between the intersection and the union of a family of sets?
The intersection of a family of sets includes elements that are common to all sets in the family. The union includes all elements that are in at least one set in the family.
Which of the following statements is TRUE about the intersection of a family of sets (Ai)i∈I?
Which of the following statements is TRUE about the intersection of a family of sets (Ai)i∈I?
Match the following symbols with their corresponding operations on families of sets:
Match the following symbols with their corresponding operations on families of sets:
In the example given, A1 = {1, 2, 3, 4,...}, A2 = {2, 4, 6, 8,...}, ... . The intersection of all these sets, denoted by ∩i∈I Ai, is the set {12, 24, 36, 48,...}. This means that the intersection contains all ______ of all sets Ai.
In the example given, A1 = {1, 2, 3, 4,...}, A2 = {2, 4, 6, 8,...}, ... . The intersection of all these sets, denoted by ∩i∈I Ai, is the set {12, 24, 36, 48,...}. This means that the intersection contains all ______ of all sets Ai.
The union of sets includes elements that are in exactly one set.
The union of sets includes elements that are in exactly one set.
Explain the meaning of the symbol '∃' in the context of sets?
Explain the meaning of the symbol '∃' in the context of sets?
What is the term used to describe the set of all mappings from A to B?
What is the term used to describe the set of all mappings from A to B?
A correspondence is a mapping if and only if for every element of A, there is only one corresponding element in B.
A correspondence is a mapping if and only if for every element of A, there is only one corresponding element in B.
What is the notation used to represent a mapping 'f' from A to B?
What is the notation used to represent a mapping 'f' from A to B?
The element in B that corresponds to an element x in A, by the mapping f, is called the ______ of x.
The element in B that corresponds to an element x in A, by the mapping f, is called the ______ of x.
Match the following terms with their corresponding definitions:
Match the following terms with their corresponding definitions:
If (x, y) belongs to the graph G of a correspondence C from A to B, what does it signify?
If (x, y) belongs to the graph G of a correspondence C from A to B, what does it signify?
In a correspondence, an element from the domain can have multiple corresponding elements from the codomain.
In a correspondence, an element from the domain can have multiple corresponding elements from the codomain.
What term is used to describe the element of A in a correspondence (A, B, G)?
What term is used to describe the element of A in a correspondence (A, B, G)?
What is the notation used to represent the direct image of a subset X under a mapping f?
What is the notation used to represent the direct image of a subset X under a mapping f?
If a ∈ A and f(a) ∈ f(X), then a must be an element of X.
If a ∈ A and f(a) ∈ f(X), then a must be an element of X.
What is the direct image of the set X = {-2, -1, 1, 2} under the mapping f(x) = x²?
What is the direct image of the set X = {-2, -1, 1, 2} under the mapping f(x) = x²?
If X is an empty set, then the direct image of X under any mapping f is also an ______ set.
If X is an empty set, then the direct image of X under any mapping f is also an ______ set.
Which of the following statements is TRUE regarding the direct images of subsets under a mapping?
Which of the following statements is TRUE regarding the direct images of subsets under a mapping?
Match the following properties of mappings with their corresponding definitions:
Match the following properties of mappings with their corresponding definitions:
In the context of a magma (E, >), an element e of E is an identity for > if and only if γe = δe = ______
In the context of a magma (E, >), an element e of E is an identity for > if and only if γe = δe = ______
According to the provided content, a magma can have multiple identity elements.
According to the provided content, a magma can have multiple identity elements.
What is the condition for an element a in a magma (E, >) to be considered idempotent for >?
What is the condition for an element a in a magma (E, >) to be considered idempotent for >?
Which of the following statements accurately describes the concept of a left invertible element 'a' in a unitary magma (E, >) with identity element 'e'?
Which of the following statements accurately describes the concept of a left invertible element 'a' in a unitary magma (E, >) with identity element 'e'?
In the monoid (N, +), every element is invertible.
In the monoid (N, +), every element is invertible.
Match the following terms with their appropriate definitions:
Match the following terms with their appropriate definitions:
Which of the following statements is true regarding the mapping f: A -> B and a family of subsets (Yi)i∈I of B?
Which of the following statements is true regarding the mapping f: A -> B and a family of subsets (Yi)i∈I of B?
For any subset X of A, f(X) is always a subset of f^(-1)(f(X))?
For any subset X of A, f(X) is always a subset of f^(-1)(f(X))?
In Proposition 5.5, what is the implication of the statement '∀ X ∈ P(A), we have X ⊆ f^(-1)(f(X))'?
In Proposition 5.5, what is the implication of the statement '∀ X ∈ P(A), we have X ⊆ f^(-1)(f(X))'?
A mapping f: A -> B is ______ if and only if for any subset X of A, f^(-1)(f(X)) = X.
A mapping f: A -> B is ______ if and only if for any subset X of A, f^(-1)(f(X)) = X.
Match the following conditions with their corresponding property of a mapping:
Match the following conditions with their corresponding property of a mapping:
Which of the following is NOT a condition equivalent to f being injective?
Which of the following is NOT a condition equivalent to f being injective?
If f(X ∩ X') = f(X) ∩ f(X') for all X, X' ∈ P(A), then f is necessarily injective.
If f(X ∩ X') = f(X) ∩ f(X') for all X, X' ∈ P(A), then f is necessarily injective.
Describe the relationship between the surjectivity of a mapping f: A -> B and the image of the preimage of a subset Y of B.
Describe the relationship between the surjectivity of a mapping f: A -> B and the image of the preimage of a subset Y of B.
Which of the following is NOT a characteristic of a mapping?
Which of the following is NOT a characteristic of a mapping?
The correspondence defined in Example 1.1 is a mapping.
The correspondence defined in Example 1.1 is a mapping.
What is the name given to the mapping that maps each element of a set to itself?
What is the name given to the mapping that maps each element of a set to itself?
The image or range of a mapping f is denoted by ______.
The image or range of a mapping f is denoted by ______.
Match the following mappings with their descriptions:
Match the following mappings with their descriptions:
Two mappings f and g are equal if they have the same domain and codomain.
Two mappings f and g are equal if they have the same domain and codomain.
What is the restriction of a mapping f to a subset X of its domain?
What is the restriction of a mapping f to a subset X of its domain?
The composition of two mappings f: A → B and g: B → C is possible if:
The composition of two mappings f: A → B and g: B → C is possible if:
Flashcards
Intersection of Sets
Intersection of Sets
The intersection is the set of elements common to all sets in a family.
Union of Sets
Union of Sets
The union is the set of elements that belong to at least one set in a family.
Symbol for Intersection
Symbol for Intersection
Denoted by '∩', represents the intersection of sets.
Symbol for Union
Symbol for Union
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Notation for Intersection
Notation for Intersection
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Notation for Union
Notation for Union
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Existential Quantifier
Existential Quantifier
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Universal Quantifier
Universal Quantifier
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Indexed Family of Sets
Indexed Family of Sets
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Correspondence
Correspondence
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Mapping
Mapping
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Graph of a Mapping
Graph of a Mapping
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Preimage
Preimage
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Unique Element in Mapping
Unique Element in Mapping
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Identity Mapping
Identity Mapping
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Image of a Mapping
Image of a Mapping
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First Projection Mapping
First Projection Mapping
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Second Projection Mapping
Second Projection Mapping
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Equal Mappings
Equal Mappings
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Restriction of a Mapping
Restriction of a Mapping
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Composition of Mappings
Composition of Mappings
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Cartesian Product
Cartesian Product
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Direct Image
Direct Image
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Condition for f(X) = ∅
Condition for f(X) = ∅
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Subset Image Property
Subset Image Property
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Union of Images
Union of Images
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Intersection of Images
Intersection of Images
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Element Mapping
Element Mapping
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Example of Mapping
Example of Mapping
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Existence of Preimage
Existence of Preimage
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Inverse Mapping
Inverse Mapping
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Injective Function
Injective Function
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Proposition: Injective
Proposition: Injective
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Surjective Function
Surjective Function
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Proposition: Surjective
Proposition: Surjective
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Subset Relation
Subset Relation
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Intersection Mapping
Intersection Mapping
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Left Identity
Left Identity
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Right Identity
Right Identity
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Idempotent Element
Idempotent Element
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Invertible Element
Invertible Element
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Magma
Magma
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Unitary Magma
Unitary Magma
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Monoid
Monoid
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Associative Property
Associative Property
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Study Notes
Logic and Theory of Sets
- Logic: A tool for reasoning about the truth and falsity of mathematical statements.
- Statement/Proposition: An assertion that is either true or false, but never both simultaneously.
- Example: "1 + 0 = 1" is a true statement.
- Example: "x≤ 9" is not a statement as x is not specified.
- Truth Value: Assigned to a statement, denoted by T (true) or F (false).
- Compound Statements: Formed by joining statements using logical connectors.
- Logical Connectors:
- Negation (˥P):
- True when P is false.
- False when P is true.
- Conjunction (P∧Q):
- True when both P and Q are true.
- False otherwise.
- Disjunction (PVQ):
- False when both P and Q are false.
- True otherwise.
- Implication (P⇒Q):
- False when P is true and Q is false.
- True otherwise.
- Equivalence (P⇔Q):
- True when P and Q have the same truth value.
- False otherwise.
- Negation (˥P):
- Tautology: A compound statement that is always true, regardless of the truth values of its component statements.
- Contradiction: A compound statement that is always false, regardless of the truth values of its component statements.
- Principle of Non-Contradiction: The statement P ∧ ˥P is a contradiction.
- Law of the Excluded Middle: The statement P ∨ ˥P is a tautology.
Sets
- Set: An unordered collection of distinct objects (elements/members).
- Set Membership: x ∈ A, means x is an element of A. x ∉ A means x is not an element of A.
- Extensional Definition of a Set: Listing all elements within braces.
- Intentional Definition of a Set: Defining the elements via a property.
- Example: {x ∈ Ν / 1 ≤ x ≤ 7}
- Singleton: A set with exactly one element.
- Doubleton: A set with exactly two elements.
- Tripleton: A set with exactly three elements.
- Empty Set: A set with no elements (denoted by Ø).
- Subset (A ⊆ B): Every element in A is also in B.
- Proper Subset (A ⊂ B): A ⊆ B and A ≠ B (A is a subset of B but not equal to B).
- Power Set (P(A)): The set of all subsets of A.
Operations on Sets
- Intersection (A ∩ B): Elements belonging to both A and B.
- Union (A ∪ B): Elements belonging to A or B (or both).
- Disjoint Sets (A ∩ B = Ø): Sets with no common elements.
- Relative Complement (CSA or A – B): Elements in S but not in A.
- Equality of Sets (A = B): If two sets A and B have the same elements.
Mappings/Functions
-
Correspondence: A relationship from a set A to a set B.
-
Mapping/Function: A correspondence from A to B where, for every element of A, there is a unique corresponding element in B.
-
Image (f(x)): The element in B associated with x in A.
-
Preimage: elements in A which correspond to a given element in B
-
Restriction of a function: A function defined only on a subset of the domain
-
Identity Mapping (IdA): Each element maps to itself.
-
Image or range of f (Imf): The set of all images of elements in A.
-
Injective (Injection): Each element in the codomain has at most one preimage in the domain
-
Surjective (Surjection): Each element in the codomain has at least one preimage in the domain
-
Bijective: Both injective and surjective
-
Composite Mapping (go f): The output of g applied to the output of f.
Subsets and Power Set
- Subset: A set A is a subset of a set B if every element of A is also an element of B.
- Proper subset: A is a proper subset of B if A is a subset of B and A is not equal to B.
- Power set: the power set of a set is the set of all subsets of that set.
Methods of Proof
- Direct Proof: Assume the premise is true, and show that the conclusion is also true.
- Proof by Contraposition: Prove the contrapositive of the implication.
- Proof by Contradiction: Assume the negation of the statement is true, and derive a contradiction.
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