Propositional logic & proofs worksheet with answers

Free printable Propositional logic & proofs worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
abc(b ∧ ¬a) ∧ (c ∧ (¬b → c))111110101100011010001000

Exactly one row of the truth table makes (b ∧ ¬a) ∧ (c ∧ (¬b → c)) true. Click that row.

(b ∧ ¬a) ∧ (c ∧ (¬b → c))
  1. 1a = 1, b = 1, c = 1
  2. 2a = 1, b = 1, c = 0
  3. 3a = 1, b = 0, c = 1
  4. 4a = 1, b = 0, c = 0
  5. 5a = 0, b = 1, c = 1
  6. 6a = 0, b = 1, c = 0
  7. 7a = 0, b = 0, c = 1
  8. 8a = 0, b = 0, c = 0
2.Easy
pqp → (p ∧ q)11100100

Exactly one row of the truth table makes p → (p ∧ q) false. Click that row.

p → (p ∧ q)
  1. 1p = 1, q = 1
  2. 2p = 1, q = 0
  3. 3p = 0, q = 1
  4. 4p = 0, q = 0
3.Medium
¬q → ¬(r ∨ p)¬q ∧ ¬(r ∨ p)¬q ∧ (r ∨ p)q ∧ ¬(r ∨ p)

You want to prove q → (r ∨ p) by contradiction. Which statement do you assume at the start? Click it.

q → (r ∨ p)
  1. 1¬q → ¬(r ∨ p)
  2. 2¬q ∧ ¬(r ∨ p)
  3. 3¬q ∧ (r ∨ p)
  4. 4q ∧ ¬(r ∨ p)
4.Medium
tautologycontradictioncontingency

Is a ∧ ¬a a tautology, a contradiction or a contingency? Click your answer.

a ∧ ¬a
  1. 1tautology
  2. 2contradiction
  3. 3contingency
5.Hard

How many of the 16 rows of the truth table make ((d → c) ∧ (b ∨ ¬c)) → ((b ∨ ¬d) ∧ a) true? Call this number N.

((d → c) ∧ (b ∨ ¬c)) → ((b ∨ ¬d) ∧ a)
N =
6.Hard
pqrq → (r ∨ p)qr111110101100011010001000

The argument with premises q → (r ∨ p); q and conclusion r is invalid. Click the row of the truth table that is a counterexample.

q → (r ∨ p)q∴ r
  1. 1p = 1, q = 1, r = 1
  2. 2p = 1, q = 1, r = 0
  3. 3p = 1, q = 0, r = 1
  4. 4p = 1, q = 0, r = 0
  5. 5p = 0, q = 1, r = 1
  6. 6p = 0, q = 1, r = 0
  7. 7p = 0, q = 0, r = 1
  8. 8p = 0, q = 0, r = 0

Answer key

  1. 1. a = 0, b = 1, c = 1
  2. 2. p = 1, q = 0
  3. 3. q ∧ ¬(r ∨ p)
  4. 4. contradiction
  5. 5. N = 12
  6. 6. p = 1, q = 1, r = 0

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