Given any proposition variables p, q, and r, a tautology t and a contradiction c, the following logical equivalences hold:
1. Idempotent Laws
a. p ∨ q ≡ p
b. p ∧ q ≡ p
.
2. Involution Law
~~p ≡ p
.
3. Commutative Laws
a. p ∨ q ≡ q ∨ p
b. p ∧ q ≡ q ∧ p
.
4. Associative Laws
a. (p ∨ q) ∨ r ≡ p ∨ (q ∨ r)
b. (p ∧ q) ∧ r ≡ p ∧ (q ∧ r)
.
5. Distributive Laws
a. p ∨ (q ∧ r) ≡ (p ∨ q) ∧ (p ∨ r)
b. p ∧ (q ∨ r) ≡ (p ∧ q) ∨ (p ∧ r)
.
6. Identity Laws
a. p ∨ c ≡ p
b. p ∧ t ≡ p
c. p ∨ t ≡ t
d. p ∧ c ≡ c
.
7. Complement Laws
a. p ∨ ~p ≡ t
b. p ∧ ~p ≡ c
c. ~t ≡ c
d. ~c ≡ t
.
8. Absorption Laws
a. p ∧ (p ∨ q) ≡ p
b. p ∨ (p ∧ q) ≡ p
.
9 DeMorgan's Law
a. ~(p ∨ q) ≡ ~p ∧ ~q
b. ~(p ∧ q) ≡ ~p ∨ ~q