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(q ∨ ¬p) → ((¬p ∧ q) → r)111110101100011010001000

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

(q ∨ ¬p) → ((¬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
2.Easy
pqrq → (r → ¬p)111?110?101?100?011?010?001?000?

Complete the truth table (1 = true, 0 = false). In how many rows N is q → (r → ¬p) true?

q → (r → ¬p)
N =
3.Medium
pqr¬q ∨ ¬r¬p ∧ (¬q ∨ ¬r)(¬r ↔ (q → p)) ∧ (¬p ∧ (¬q ∨ ¬r))111?110?101?100?011?010?001?000?

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

(¬r ↔ (q → p)) ∧ (¬p ∧ (¬q ∨ ¬r))
N =
4.Medium
(b ∨ c) ∧ ¬a¬a → ¬(b ∨ c)¬(b ∨ c) → ¬aa → (b ∨ c)

You want to prove (b ∨ c) → a by contrapositive. Which implication do you prove instead? Click it.

(b ∨ c) → a
  1. 1(b ∨ c) ∧ ¬a
  2. 2¬a → ¬(b ∨ c)
  3. 3¬(b ∨ c) → ¬a
  4. 4a → (b ∨ c)
5.Hard

How many of the 16 rows of the truth table make (¬q → (r → s)) → ((¬r ↔ ¬q) ∧ ¬p) true? Call this number N.

(¬q → (r → s)) → ((¬r ↔ ¬q) ∧ ¬p)
N =
6.Hard
p ∧ rp¬rr

The premises p ∨ r; ¬p are given. Which conclusion follows from them? Click it.

p ∨ r¬p
  1. 1p ∧ r
  2. 2p
  3. 3¬r
  4. 4r

Answer key

  1. 1. p = 0, q = 1, r = 0
  2. 2. N = 7
  3. 3. N = 1
  4. 4. ¬a → ¬(b ∨ c)
  5. 5. N = 6
  6. 6. r

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