Truth Table Flashcards: Connectives & Logical Equivalence
84 truth-table flashcards on logical connectives, material conditionals, nested expressions, equivalence, and counterexamples, with short explanations.
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Practice propositional logic with 84 English truth-table flashcards. The set covers NOT (¬), AND (∧), inclusive OR (∨), exclusive OR (⊕), the material conditional (→), and the biconditional (↔). T means true and F means false. It suits learners starting formal logic or discrete mathematics.
Cards ask you to recall a connective’s truth conditions, identify a connective from its full rule, evaluate an expression from a stated assignment, and produce short output columns with an explicit row order. A few original statement-to-symbol tasks and one symbol-to-statement task connect the notation to English. Later cards practice De Morgan’s laws, double negation, conditional rewriting, biconditional and XOR expansions, negated conditionals, and the distinction between a conditional, its converse, inverse, and contrapositive.
The sequence introduces notation and simple connectives before nested expressions, logical equivalence, counterexamples, and tautology/contradiction/contingency classification. Selected equivalences have separate forward and reverse cards, placed apart. Answers start with the result and give a short reason. For a counterexample task, any assignment that makes the two outputs differ is a valid answer.
This is a focused practice set, not a full logic course or an exam syllabus. It excludes quantified statements, proof systems, circuits, and programming-language evaluation rules. It does not ask for a connective from a lone truth value, which would be ambiguous, or repeat every possible symbolic and English permutation. Material implication is used as a truth-functional rule; the cards do not treat it as a theory of causation or every everyday use of “if”.
For a short introduction, read truth values, conjunction and disjunction. For study habits, see how to use flashcards for math.
The questions, answers, examples, order, metadata, and cover were independently created with AI assistance. Logic facts were checked against the open textbook forall x: Calgary, especially its chapters on connective truth tables, complete truth tables, and semantic concepts, and by direct truth-value calculation. No textbook exercises, teaching prose, diagrams, examination questions, or competitor cards were copied. The original text and generated cover are released under CC0 1.0 to the extent applicable rights exist; reference-source text retains its own license. This is an independent resource, unaffiliated with the Open Logic Project or any school or examination provider.
Cartões deste baralho
Cartão 1
Pergunta
In classical propositional logic, what is a proposition?
Resposta
A statement with a truth value: true or false. A question or command is not a proposition in this setting.
Cartão 2
Pergunta
What does negation (¬p) do to the truth value of p?
Resposta
It reverses it: true becomes false, and false becomes true.
Cartão 3
Pergunta
When is the conjunction (p ∧ q) true?
Resposta
Only when p and q are both true.
Cartão 4
Pergunta
When is the inclusive disjunction (p ∨ q) true?
Resposta
When at least one of p and q is true, including when both are true.
Cartão 5
Pergunta
What does one valuation assign in a propositional truth table?
Resposta
One truth value to each proposition letter. The assignment stays fixed throughout that row.
Cartão 6
Pergunta
When is the material conditional (p → q) false?
Resposta
Only when p is true and q is false. Here p is the antecedent and q is the consequent.
Cartão 7
Pergunta
When is the biconditional (p ↔ q) true?
Resposta
When p and q have the same truth value: both true or both false.
Cartão 8
Pergunta
When is exclusive OR (p ⊕ q) true?
Resposta
When exactly one of p and q is true. It is false when their truth values match.
Cartão 9
Pergunta
What is the main connective in ((¬p) ∧ q)?
Resposta
∧ (AND). It combines the whole left part, (¬p), with q.
Cartão 10
Pergunta
How many rows does a complete truth table with three distinct proposition letters need?
Resposta
8 rows: each of the three letters has two choices, so 2³ = 8.
Cartão 11
Pergunta
If p = F, what is (¬p)?
Resposta
T. Negation reverses F to T.
Cartão 12
Pergunta
If p = T and q = F, what is (p ∧ q)?
Resposta
F. AND needs both inputs to be true.
Cartão 13
Pergunta
If p = T and q = T, what is inclusive OR (p ∨ q)?
Resposta
T. Inclusive OR allows both inputs to be true.
Cartão 14
Pergunta
If p = T and q = T, what is the material conditional (p → q)?
Resposta
T. A true antecedent with a true consequent does not make the conditional false.
Cartão 15
Pergunta
If p = F and q = F, what is (p ↔ q)?
Resposta
T. The two truth values match, even though neither is true.
Cartão 16
Pergunta
If p = T and q = T, what is exclusive OR (p ⊕ q)?
Resposta
F. XOR requires exactly one true input.
Cartão 17
Pergunta
Does a true material conditional (p → q) establish that p causes q?
Resposta
No. Material implication is determined by truth values; it does not establish causation or capture every everyday use of “if”.
Cartão 18
Pergunta
What assignments are listed by the two-letter row order TT, TF, FT, FF?
Resposta
(p, q) = (T, T), (T, F), (F, T), (F, F). Each possible assignment appears once.
Cartão 19
Pergunta
In ¬(p ∨ q), does ¬ negate just p or the whole disjunction?
Resposta
The whole disjunction (p ∨ q). Evaluate that parenthesized expression before negating it.
Cartão 20
Pergunta
If p = F and q = T, what is the material conditional (p → q)?
Resposta
T. A material conditional with a false antecedent is true.
Cartão 21
Pergunta
If p = T and q = F, what is (p ↔ q)?
Resposta
F. The two truth values differ.
Cartão 22
Pergunta
If p = T and q = F, what is exclusive OR (p ⊕ q)?
Resposta
T. Exactly one input is true.
Cartão 23
Pergunta
Which standard connective is true exactly when both inputs are true?
Resposta
Conjunction (AND), written ∧.
Cartão 24
Pergunta
Which standard connective is false exactly when both inputs are false?
Resposta
Inclusive disjunction (OR), written ∨. The both-true case is true.
Cartão 25
Pergunta
Which standard connective takes one input and reverses its truth value?
Resposta
Negation (NOT), written ¬.
Cartão 26
Pergunta
If p = F and q = F, what is the material conditional (p → q)?
Resposta
T. Its only false case requires a true antecedent and a false consequent.
Cartão 27
Pergunta
Which standard connective is true exactly when its two inputs have matching truth values?
Resposta
The biconditional (if and only if), written ↔.
Cartão 28
Pergunta
Which standard connective is true exactly when its two inputs have different truth values?
Resposta
Exclusive OR (XOR), written ⊕.
Cartão 29
Pergunta
What is the main connective in ((p ∨ q) → (¬r))?
Resposta
→ (the material conditional). The entire disjunction is the antecedent, and (¬r) is the consequent.
Cartão 30
Pergunta
Which standard connective is false exactly when its first input is true and its second input is false?
Resposta
The material conditional, written →. Input order matters.
Cartão 31
Pergunta
Give the output column for (p ∧ q), with (p, q) rows TT, TF, FT, FF.
Resposta
T, F, F, F. Only the both-true row satisfies AND.
Cartão 32
Pergunta
If p = T and q = F, what is ¬(p ∧ q)?
Resposta
T. First (p ∧ q) is F; negating it gives T.
Cartão 33
Pergunta
Let a mean “the archive is open” and b mean “the desk is staffed”. Symbolize “the archive is open and the desk is staffed”.
Resposta
(a ∧ b). Both statements are asserted.
Cartão 34
Pergunta
Give the output column for the material conditional (p → q), with (p, q) rows TT, TF, FT, FF.
Resposta
T, F, T, T. Only the true-antecedent, false-consequent row fails.
Cartão 35
Pergunta
What makes a formula a tautology in classical propositional logic?
Resposta
It is true on every possible valuation, not just the row currently being checked.
Cartão 36
Pergunta
Give the output column for inclusive OR (p ∨ q), with (p, q) rows TT, TF, FT, FF.
Resposta
T, T, T, F. Only the both-false row fails inclusive OR.
Cartão 37
Pergunta
When are two propositional formulas logically equivalent?
Resposta
When their final truth values match on every valuation of their combined proposition letters.
Cartão 38
Pergunta
Give the output column for (p ↔ q), with (p, q) rows TT, TF, FT, FF.
Resposta
T, F, F, T. The first and last rows have matching truth values.
Cartão 39
Pergunta
If p = F and q = T, what is (p ∨ (¬q)), using inclusive OR?
Resposta
F. Both p and (¬q) are F.
Cartão 40
Pergunta
If p = T and q = F, what is the material conditional (p → q)?
Resposta
F. This is its only false input combination.
Cartão 41
Pergunta
Give the output column for (¬p), with p rows T, F.
Resposta
F, T. Negation reverses each row.
Cartão 42
Pergunta
Let s mean “the scan succeeds” and a mean “the alert appears”. Symbolize “if the scan succeeds, the alert appears”, using material implication.
Resposta
(s → a). The scan statement is the antecedent; the alert statement is the consequent.
Cartão 43
Pergunta
Give the output column for exclusive OR (p ⊕ q), with (p, q) rows TT, TF, FT, FF.
Resposta
F, T, T, F. Exactly one input is true in the middle two rows.
Cartão 44
Pergunta
What makes a formula a contradiction in classical propositional logic?
Resposta
It is false on every possible valuation.
Cartão 45
Pergunta
If p = T, q = F and r = T, what is ((p ∧ q) ∨ r), using inclusive OR?
Resposta
T. The conjunction is F, but r is T, so the disjunction is T.
Cartão 46
Pergunta
Simplify ¬(¬p) without changing its truth value.
Resposta
p. Two negations restore the original truth value.
Cartão 47
Pergunta
Let d mean “the door is unlocked” and c mean “the code is accepted”. Symbolize “the door is unlocked if and only if the code is accepted”.
Resposta
(d ↔ c). Both directions of the conditional are required.
Cartão 48
Pergunta
What makes a propositional formula contingent?
Resposta
It is true on at least one valuation and false on at least one other valuation.
Cartão 49
Pergunta
If p = T and q = T, what is (p → (¬q)), using material implication?
Resposta
F. Its antecedent is T and its consequent (¬q) is F.
Cartão 50
Pergunta
Use De Morgan’s law to rewrite ¬(p ∧ q) with negations only on letters.
Resposta
((¬p) ∨ (¬q)). At least one conjunct must be false; ∨ is inclusive OR.
Cartão 51
Pergunta
Let n mean “the north path is open” and e mean “the east path is open”. Symbolize “at least one of these paths is open, possibly both”.
Resposta
(n ∨ e). This is inclusive OR.
Cartão 52
Pergunta
Classify (p ∨ (¬p)): tautology, contradiction or contingent? Use classical logic and inclusive OR.
Resposta
Tautology. Whether p is T or F, one disjunct is T.
Cartão 53
Pergunta
If p = F and q = F, what is ¬(p ∨ q), using inclusive OR?
Resposta
T. The disjunction is F, so its negation is T.
Cartão 54
Pergunta
Use De Morgan’s law to rewrite ¬(p ∨ q) with negations only on letters. Use inclusive OR.
Resposta
((¬p) ∧ (¬q)). Both disjuncts must be false.
Cartão 55
Pergunta
Let w mean “the window is closed” and h mean “the heater is on”. Read (h → w) as an English material conditional.
Resposta
If the heater is on, then the window is closed. The formula itself makes no causal claim.
Cartão 56
Pergunta
Classify (p ∧ (¬p)): tautology, contradiction or contingent?
Resposta
Contradiction. The two conjuncts cannot both be true on any valuation.
Cartão 57
Pergunta
Rewrite the material conditional (p → q) using only NOT and inclusive OR.
Resposta
((¬p) ∨ q). It is false exactly when p is T and q is F.
Cartão 58
Pergunta
If p = T, q = T and r = F, what is ((p ⊕ q) ↔ r), where ⊕ is exclusive OR?
Resposta
T. The XOR is F and r is F, so the biconditional compares matching values.
Cartão 59
Pergunta
Write an expression with exactly two NOT operators that is equivalent to p.
Resposta
¬(¬p). Negating twice leaves every truth value unchanged.
Cartão 60
Pergunta
Classify (p ∧ q): tautology, contradiction or contingent?
Resposta
Contingent. It is T at p = T, q = T and F at p = F, q = T.
Cartão 61
Pergunta
What is the contrapositive of the material conditional (p → q)?
Resposta
((¬q) → (¬p)). Swap the two sides and negate both.
Cartão 62
Pergunta
Rewrite ¬(p → q) using AND and NOT, with → meaning material implication.
Resposta
(p ∧ (¬q)). A material conditional fails exactly when its antecedent is true and its consequent is false.
Cartão 63
Pergunta
Rewrite ((¬p) ∨ (¬q)) as one negation of a conjunction, using inclusive OR.
Resposta
¬(p ∧ q). This is De Morgan’s law in the reverse direction.
Cartão 64
Pergunta
Give the output column for (p ∨ (¬q)), with (p, q) rows TT, TF, FT, FF and inclusive OR.
Resposta
T, T, F, T. The only false row has p = F and q = T.
Cartão 65
Pergunta
What is the converse of (p → q)?
Resposta
(q → p). Swap the antecedent and consequent without negating either.
Cartão 66
Pergunta
Rewrite (p ↔ q) as an AND of two material conditionals.
Resposta
((p → q) ∧ (q → p)). Both directions must hold.
Cartão 67
Pergunta
Rewrite ((¬p) ∧ (¬q)) as one negation of an inclusive disjunction.
Resposta
¬(p ∨ q). This is De Morgan’s law in the reverse direction.
Cartão 68
Pergunta
Give one valuation showing that (p ∨ q) and (p ∧ q) are not equivalent. Use inclusive OR.
Resposta
p = T, q = F gives T for the OR and F for the AND. The swapped assignment also works.
Cartão 69
Pergunta
What is the inverse of (p → q)?
Resposta
((¬p) → (¬q)). Negate both sides without swapping them.
Cartão 70
Pergunta
Rewrite ((¬p) ∨ q) as a single material conditional, using inclusive OR.
Resposta
(p → q). Both expressions fail exactly when p is T and q is F.
Cartão 71
Pergunta
Rewrite exclusive OR (p ⊕ q) using AND, inclusive OR and NOT.
Resposta
((p ∨ q) ∧ ¬(p ∧ q)). Require at least one true input and rule out both being true.
Cartão 72
Pergunta
A formula is true for p = T and q = F. Is that enough to call it a tautology?
Resposta
No. A tautology must be true on every valuation. One true row establishes only that it can be true.
Cartão 73
Pergunta
Is a material conditional (p → q) logically equivalent to its contrapositive ((¬q) → (¬p))?
Resposta
Yes. Both are false exactly when p is T and q is F.
Cartão 74
Pergunta
Give one valuation showing that (p → q) and its converse (q → p) are not equivalent. Use material implication.
Resposta
p = T, q = F. Then (p → q) is F and (q → p) is T.
Cartão 75
Pergunta
Rewrite ((p → q) ∧ (q → p)) using one connective, with both arrows meaning material implication.
Resposta
(p ↔ q). This is the biconditional.
Cartão 76
Pergunta
What does one valuation with different outputs prove about two formulas?
Resposta
They are not logically equivalent. Equivalence requires agreement on every valuation.
Cartão 77
Pergunta
Give one valuation showing that (p → q) and its inverse ((¬p) → (¬q)) are not equivalent. Use material implication.
Resposta
p = T, q = F. The original is F, while the inverse has a false antecedent and is T.
Cartão 78
Pergunta
Give one valuation showing that ¬(p ∧ q) and ((¬p) ∧ (¬q)) are not equivalent.
Resposta
p = T, q = F. The negated conjunction is T; the conjunction of negations is F.
Cartão 79
Pergunta
Which connective does ((p ∨ q) ∧ ¬(p ∧ q)) express? Here ∨ is inclusive OR.
Resposta
Exclusive OR: (p ⊕ q). Exactly one input must be true.
Cartão 80
Pergunta
If (p ↔ q) is true on one row, does that show that the formulas p and q are logically equivalent?
Resposta
No. They match on that row only. Logical equivalence requires the biconditional to be true on every valuation.
Cartão 81
Pergunta
Are the converse (q → p) and inverse ((¬p) → (¬q)) of (p → q) equivalent to each other? Use material implication.
Resposta
Yes. They are contrapositives of each other, and both are false exactly when q is T and p is F.
Cartão 82
Pergunta
At p = T, q = F and r = F, compare ((p ∨ q) ∧ r) with (p ∨ (q ∧ r)). Use inclusive OR.
Resposta
The first is F; the second is T. Parentheses change which operations combine first.
Cartão 83
Pergunta
Rewrite (p ∧ (¬q)) as the negation of one material conditional.
Resposta
¬(p → q). The conjunction describes exactly the conditional’s false case.
Cartão 84
Pergunta
Among AND (∧), inclusive OR (∨), XOR (⊕), material conditional (→) and biconditional (↔), which has outputs T, F, F, T for (p, q) rows TT, TF, FT, FF?
Resposta
Biconditional (↔). It is true on the two rows where the inputs match.
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Truth Table Flashcards: Connectives & Logical Equivalence
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