14. 5.1
EXACT COVER BY 3-SET
• NP NP
• NP NP EXACT EXACT COVER BY 3-SET
COVER BY 3-SET
EXACT COVER BY 3-SET
• EXACT COVER BY 3-SET
5.2 3 X 3 X
S = {T 1, T 2, ...} S1 ⊂ S
NP
(1) ∪{T |T ∈ S1 } = X
5.4. X S1 135
134 5
(2) i=j Ti ∩ Tj = φ S 1
5.4 EXACT COVER BY 3-SET
1 2 3 {{1, 4, 7}, {2, 3, 5}, {6, 8, 9}}
X EXACT COVER
BY 3-SET 4 5 6 EXACT COVER
: NP BY 3-SET
7 8 9
14
15. BY 3-SET
•: NP
•
•
X 1 |X|
• X Y = {y1 , y2 , ..., y|X| } |X| 0 Y
t X Y Y = {y1 , y2 , . . . X |X| }
,y 1 Y
• t 0X Y X 1 Y 0
1 t∈X
t[A] =
0 t∈Y
X 3 T1 , T 2 , . . .
1 0 yi
1
1 t ∈ Ti 1 t = yi
16. 0 t∈Y
•X X 3
3
T1 , T 2 , . . . T1 , T 2 , . . .
1 1 0 0 yi
• yi 1 1
1 t ∈ Ti 1 t = yi
t[Ti ] = , t[yi ] =
0 t ∈ Ti 0 t = yi
•
Ti yi
•
• 2
• Ti
9 3 5.5(A)
• 5.5(B)
17. •
• |X|
|X| |X|
1 + 2 + ··· + +
3 3
•
• EXACT COVER BY 3-SET
136 EXACT COVER BY 3-SET5
: :
Y T1 T2 T3
yi yi
T1
|Y | = |X| 9
5.6(A) 1 T2
1 T3
1 + 2 + · · · + |X| + |X|1 0
(A) (B)