(a ⊕ b) ⊕ c = ((a ∧ b) ∨ (a ∧ b)) ⊕ c =
=
¡
((a ∧ b) ∨ (a ∧ b)) ∧ c
¢
∨
³
((a ∧ b) ∨ (a ∧ b)) ∧ c
´
=
=
¡
(a ∧ b ∧ c) ∨ (a ∧ b ∧ c)
¢
∨
¡
((a ∨ b) ∧ (a ∨ b)) ∧ c
¢
=
= (a ∧ b ∧ c) ∨ (a ∧ b ∧ c) ∨
( (a ∧ a)
| {z }
=0
∨(a ∧ b) ∨ (b ∧ a) ∨ (b ∧ b)
|{z }
=0
) ∧ c
=
= (a ∧ b ∧ c) ∨ (a ∧ b ∧ c) ∨
¡
((a ∧ b) ∨ (a ∧ b)) ∧ c
¢
=
= (a ∧ b ∧ c) ∨ (a ∧ b ∧ c) ∨ (a ∧ b ∧ c) ∨ (a ∧ b ∧ c) =
= (a ∧ b ∧ c) ∨ (a ∧ b ∧ c) ∨ (a ∧ b ∧ c) ∨ (a ∧ b ∧ c).
a b
c
¿
⊕
À
(b⊕c)⊕a (b⊕c)⊕a
(a⊕b)⊕c
a b c
¿
·
À
(a ⊕ b) · c = ((a ∧ b) ∨ (a ∧ b)) ∧ c = (a ∧ b ∧ c) ∨ (a ∧ b ∧ c);
a · c ⊕ b · c = ((a ∧ c) ∧ (b ∧ c)) ∨ ((a ∧ c) ∧ (b ∧ c)) =
= (a ∧ c ∧ (b ∨ c)) ∨ ((a ∨ c) ∧ b ∧ c) = (a ∧ c ∧ b) ∨ (a ∧ b ∧ c)
¿
·
À
hA, ⊕, ·i 1 ∈ A A