?2?

?⇢?

? 2 {?}

? ⇢ {?}

A[B =B , A⇢B , A\B =A A, B ⇢ U (A [ B)C = AC \ B C (A \ B)C = AC [ B C U Q R

P Q A B C R

R U

P P Q A B

A \ BC ⇢ C

AC [ B C ⇢ C

AC ⇢ B C [ C

A ⇢ BC [ C C

C

AC [ B ⇢ C C

B \ A = {x ; x 2 B e x 2 / A}.

B\A=;

B⇢A

B\A=B

A\B =; B\A=A\B

A=B

A \ (B \ C) = (A \ B) \ C.

p

x+x = 2

p

x=1, , , ,

x+3=x

x2 2x + 1 = 0 x2 2 · 1 + 1 = 0 x2 1 = 0 x = ±1

x = 1 , x = ±1

A B

C

A [ (B \ C) = (A [ B) \ C.

P (x) x x

P (x) P (x)

x A

x P (x)

U

x n x x

x2 = 1 n2 > n x>1 x2 < 1 n

n>x n n>x

F M C P

x

4

P (A) A

A A f : A ! P (A) f

A; x2 / f (x)}

X = {x 2