Mathematical Logic and Set Theory

Description: Mathematical Logic and Set Theory Quiz
Number of Questions: 15
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Tags: mathematical logic set theory propositional logic predicate logic proofs
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Which of the following is a tautology in propositional logic?

  1. ¬(P ∨ Q)

  2. (P → Q) → ¬P

  3. P ∨ (¬P ∧ Q)

  4. ¬(P ∧ Q) → (¬P ∨ ¬Q)


Correct Option: D
Explanation:

The given statement is a tautology because it is true for all possible combinations of truth values of P and Q.

What is the negation of the statement "∀x ∈ R, x^2 ≥ 0"?

  1. ∃x ∈ R, x^2 < 0

  2. ∀x ∈ R, x^2 > 0

  3. ∃x ∈ R, x^2 ≤ 0

  4. ∀x ∈ R, x^2 ≠ 0


Correct Option: A
Explanation:

The negation of a universal statement is an existential statement with the opposite quantifier and the opposite truth value.

Which of the following is a valid inference rule in propositional logic?

  1. Modus Ponens

  2. Modus Tollens

  3. Hypothetical Syllogism

  4. Disjunctive Syllogism


Correct Option: A
Explanation:

Modus Ponens is a valid inference rule that allows us to infer P from the premises P → Q and Q.

What is the power set of the set {1, 2, 3}?

  1. {{1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}, ∅}

  2. {{1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}}

  3. {{1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}}

  4. {{1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}, ∅, {∅}}


Correct Option: A
Explanation:

The power set of a set is the set of all subsets of that set.

Which of the following is an example of a bijection?

  1. The function f: R → R defined by f(x) = x^2

  2. The function g: R → R defined by g(x) = x + 1

  3. The function h: R → R defined by h(x) = sin(x)

  4. The function j: R → R defined by j(x) = |x|


Correct Option: B
Explanation:

A bijection is a function that is both one-to-one and onto.

What is the cardinality of the set of all subsets of the set {1, 2, 3}?

  1. 2^3

  2. 3^2

  3. 2^4

  4. 3^3


Correct Option: A
Explanation:

The cardinality of the set of all subsets of a set with n elements is 2^n.

Which of the following is an example of a countable set?

  1. The set of all natural numbers

  2. The set of all rational numbers

  3. The set of all real numbers

  4. The set of all functions from R to R


Correct Option: A
Explanation:

A countable set is a set that can be put into one-to-one correspondence with the set of natural numbers.

What is the complement of the set {x ∈ R | x^2 < 4}?

  1. {x ∈ R | x^2 ≥ 4}

  2. {x ∈ R | x^2 > 4}

  3. {x ∈ R | x^2 ≤ 4}

  4. {x ∈ R | x^2 ≠ 4}


Correct Option: A
Explanation:

The complement of a set is the set of all elements that are not in that set.

Which of the following is an example of a valid argument in first-order logic?

  1. All men are mortal. Socrates is a man. Therefore, Socrates is mortal.

  2. All dogs are mammals. All mammals are animals. Therefore, all dogs are animals.

  3. Some birds can fly. Tweety is a bird. Therefore, Tweety can fly.

  4. No cats are dogs. Garfield is a cat. Therefore, Garfield is not a dog.


Correct Option: A
Explanation:

A valid argument is an argument in which the conclusion follows logically from the premises.

What is the negation of the statement "∃x ∈ R, x^2 = 2"?

  1. ∀x ∈ R, x^2 ≠ 2

  2. ∃x ∈ R, x^2 > 2

  3. ∀x ∈ R, x^2 < 2

  4. ∃x ∈ R, x^2 ≤ 2


Correct Option: A
Explanation:

The negation of an existential statement is a universal statement with the opposite quantifier and the opposite truth value.

Which of the following is an example of a deductive argument?

  1. The sky is blue. Therefore, the grass is green.

  2. All men are mortal. Socrates is a man. Therefore, Socrates is mortal.

  3. I saw a black cat yesterday. Therefore, all cats are black.

  4. I like chocolate ice cream. Therefore, everyone likes chocolate ice cream.


Correct Option: B
Explanation:

A deductive argument is an argument in which the conclusion is guaranteed to be true if the premises are true.

What is the cardinality of the set of all functions from the set {1, 2, 3} to the set {a, b, c}?

  1. 3^3

  2. 3^2

  3. 2^3

  4. 2^2


Correct Option: A
Explanation:

The cardinality of the set of all functions from a set with n elements to a set with m elements is m^n.

Which of the following is an example of a non-constructive proof?

  1. Proof by contradiction

  2. Proof by mathematical induction

  3. Proof by exhaustion

  4. Proof by construction


Correct Option: A
Explanation:

A non-constructive proof is a proof that shows that a statement is true without actually providing a way to construct the object that the statement claims exists.

What is the intersection of the sets {1, 2, 3} and {2, 3, 4}?

  1. {1, 2, 3, 4}

  2. {1, 2, 3}

  3. {2, 3}

  4. {1, 4}


Correct Option: C
Explanation:

The intersection of two sets is the set of all elements that are in both sets.

Which of the following is an example of a countably infinite set?

  1. The set of all natural numbers

  2. The set of all rational numbers

  3. The set of all real numbers

  4. The set of all functions from R to R


Correct Option: B
Explanation:

A countably infinite set is a set that can be put into one-to-one correspondence with the set of natural numbers.

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