1. - 䒺 .
2. . 䳿 䳺 .
3. , .
4. .
5. ³ , .
6. , 䳺 .
- 䒺
: 9 . 3 䒿. ?. : 9 − 3 = 6 (). , ( 9) , 䒿 ( 3) , , ( 6) .
. г ' b , n () = , n () = b, B A, − b = n (A\B), n () = , n () = b, B A.
г b , , n () = , n () = b B A.
:
1) A = { a, b, c, d }, B = { c, d }, B A, n (A) = 4, n (B) = 2 A\B = { a, b }, n (A\B) = 2 4 2 = 2.
2) A = {Δ, Δ, Δ, Ο}, B = {Ο}, B A, n (A) = 5, n (B) = 1
A\B = { Δ, Δ, Δ }, n (A\B) = 4 5 1 = 4.
ij, , . 䳿 () 䒺 (b).
䳺 , , ( 㳿). - .
. 䳿 䳺
, .
䒺 b , = n (A), b = n (B), B A n (A\B) = − b. A, B A\B :
A = B (A\B), n (A) = n (B (A\B)). B (A\B) = , n (A) = n (B (A\B)) = n (B) + n (A\B) = b + ( b) = b , b . : ' b 䒺 , ,
− b = c = b + .
ij 䳿 . ij . .