A
a
1
∧a
2
⊂ A
a
1
∩ A
a
2
x ∈ A
a
1
∩ A
a
2
(x ∈ A
a
1
∩A
a
2
) ⇔
(
x ∈ A
a
1
,
x ∈ A
a
2
⇔
(
x 4 a
1
,
x 4 a
2
⇒ (x 4 a
1
∧a
2
) ⇔ (x ∈ A
a
1
∧a
2
),
A
a
1
∩ A
a
2
⊂ A
a
1
∧a
2
A
a
1
∧a
2
= A
a
1
∩ A
a
2
A
a
= (A
a
)
c
x ∈ A
a
x ∧ (a ∨ a)
x ∧ (a ∨ a) = (x ∧ a) ∨ (x ∧ a) =
(
0, x /∈ A
a
x /∈ A
a
,
x, x ∈ A
a
x ∈ A
a
,
x ∧ (a ∨ a) = x
x a a x
a a
x 4 a∧a = 0 x
a a
(x ∈ A
a
) ⇔ (x /∈ A
a
) ⇔ (x ∈ (A
a
)
c
),
A
a
= (A
a
)
c
1
v
w
b
u
a
c
0
{ , , }abc
{ , }bc
{ }b
{ , }ab
{ }a
{ }c
Æ
{ , }ac
a, b, c 2
{a,b,c}
f f(0) = ∅ f(a) = {a} f(b) = {b}
f(c) = {c} f(u) = {a, b} f(v) = {a, c} f(w) = {b, c} f(1) = {a, b, c}