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
pqr(r → ¬(¬p ∧ q)) ↔ (r → p)111110101100011010001000

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

(r → ¬(¬p ∧ q)) ↔ (r → p)
  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
2.Easy

The complete truth table of ¬(¬c ↔ (a ↔ b)) → (a ∧ ¬b) is written out. In how many rows N is a = 1 and b = 0?

¬(¬c ↔ (a ↔ b)) → (a ∧ ¬b)
N =
3.Medium
(b → c) ∧ (c → b)(b → c) ∨ (c → b)b ∧ c(b → c) ∧ (¬c → ¬b)

Which formula is logically equivalent to b ↔ c? Click it.

b ↔ c
  1. 1(b → c) ∧ (c → b)
  2. 2(b → c) ∨ (c → b)
  3. 3b ∧ c
  4. 4(b → c) ∧ (¬c → ¬b)
4.Medium
pqr¬p ∨ qr → (¬p ∨ q)(q ∨ p) ∧ (r → (¬p ∨ q))111?110?101?100?011?010?001?000?

In how many of the 8 rows of its truth table is (q ∨ p) ∧ (r → (¬p ∨ q)) true? Call this number N.

(q ∨ p) ∧ (r → (¬p ∨ q))
N =
5.Hard

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

((¬b → ¬d) → a) → ((¬b ↔ c) → c)
N =
6.Hard
∃x (P(x) ∧ ¬Q(x))∀x (P(x) → ¬Q(x))∃x (¬P(x) ∧ Q(x))∀x (P(x) ∧ ¬Q(x))

Which statement is equivalent to ¬∀x (P(x) → Q(x)), with the negation moved all the way inside? Click it.

¬∀x (P(x) → Q(x))
  1. 1∃x (P(x) ∧ ¬Q(x))
  2. 2∀x (P(x) → ¬Q(x))
  3. 3∃x (¬P(x) ∧ Q(x))
  4. 4∀x (P(x) ∧ ¬Q(x))

Answer key

  1. 1. p = 0, q = 0, r = 1
  2. 2. N = 2
  3. 3. (b → c) ∧ (c → b)
  4. 4. N = 5
  5. 5. N = 14
  6. 6. ∃x (P(x) ∧ ¬Q(x))

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