1. : , , .
2. , .
3. G = (X, U), |X| = 9, |U| = 24 , .
4. .
5. K15 .
6. .
7. .
8. G = (X, U), ½X½=6; ½U½=10. GS.
9. .
10. .
. , : , . X = { x 1, x 2, , x n } . , (xi, xj) Î X, U = { u 1, u 2, , u m }.
, ,
G = (X, U) S = (x 0, x 1), (x 1, x 2), , (xl -1, xl), x 0, xl ─ ─ . , G . S . q R G q - .
, R G (. 15.23):
1 | 2 | 3 | 4 | ||
1 | 0 | 1 | 1 | 0 | . |
R = 2 | 1 | 0 | 0 | 1 | |
3 | 1 | 0 | 0 | 1 | |
4 | 0 | 1 | 1 | 0 |
. 15.23. G
:
r 2 i,j = r1,i * rj ,1 + r 2, i * rj ,2 +... + rn , i * rj , n. (1.4)
, , r 211 R2 :
r 2 1, 1 = a 11 b 11 + a 12 b 21 + a 13 b 31 + a 14 b 41 = 0 + 1*1 + 1*1 + 0 = 2.
, , r 23,3 = r 1,3 r 3,1 + r 2,3 r 3,2 + r 3,3 r 3,3 + r 4,3 r 3,4 = 1*1 + 0*0 + 0*0 + 1*1 = 2.
1 | 2 | 3 | 4 | ||
1 | 2 | 0 | 0 | 2 | . |
R2 = 2 | 0 | 2 | 2 | 0 | |
3 | 0 | 2 | 2 | 0 | |
4 | 2 | 0 | 0 | 2 |
ri , j R2 2, xi xj. , r 3,2 = 2 , x 3 x 2 2: S1 = (x 3, x 1), (x 1, x 2); S2 = (x 3, x 4), (x 4, x 2).
.
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, , . , x 0 = xl, . , , , , . G (. . 15.14, a):
S1 = (x 1, x 2), (x 2, x 3), (x 3, x 6), (x 6, x 2), (x 2, x 4) ─ ,
S2 = (x 1, x 2), (x 2, x 3), (x 3, x 6), (x 6, x 2) ─ ,
S3 = (x 6, x 2), (x 2, x 4), (x 4, x 1), (x 1, x 2), (x 2, x 3), (x 3, x 6) ─ ,
S4 = (x 1, x 2), (x 2, x 3), (x 3, x 7), (x 7, x 6) ─ ,
S5 = (x 1, x 2), (x 2, x 3), (x 3, x 7), (x 7, x 6), (x 6, x 5), (x 5, x 4), (x 4, x 1) ─ .
3 .
2 . n Cn (. 15.24, ).
. 15.24 (), - ()
1 n-1 (n ³ 3) n Wn. . 15.24, W6.
xi, xj Î X , S, xi, xj. G , . G , G1, G2, , G l . , G xi ; xi c xj, xj c xi; xi c xj, xj c xk, xi c xk (xi, xj, xk Î X).
, . G = (X, U), , G i, . , G ( ). , , . 15.14, , . 15.25 G1 ─ G4, .. . , . , , .
. 15.25.
,
n 1 £ m £ n (n 1)/2. (1.5)
15.1. G (. . 10) n k . m
n k £ m £ (n - k)(n - k + 1)/2. (1.6)
15.1. n (n 1)(n 2)/2 .
, , . G = (X, U) 2 X X, X, X Ì X, X = X \ X, X È X = X, U Ì U, X, X, G. G = (X, U\U), G , , , , . U Ì U, G = (X, U \ U) UÌU, , G = (X, U \ U), , . , G . . . 15.26, G = (X, U). .
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. 15.26. () ()
: U1 = {(x 3, x 6), (x 4, x 6), (x 4, x 7)}, U2 = {(x 4, x 10), (x 5, x 10)}, U3 = {(x 5, x 12)}, U4 = {(x 5, x 15)}, U = U1 È U2 È U3 È U4. , . G U = U U = Æ. ui Î U, ui .
, . , G . 15.26, 3 .
─ , , . ─ . G ─ , . , . 15.27 G, x 5 x 6, G 4 (. 15.28).
B(G) ─ , ─ , .
H = H(G) G , . H(G) . 1.
. 15.27. G . 15.28. G
l = l(G) , .
:
H(G) £ l(G) £ r min (G), (15.7)
r min (G) ─ .
G n-, H(G) ³ n n-, l(G) ³ n.
15.2 (). G n-, n ³ 2, , n G, .
15.3. 3 ─ , , :
1) ;
2) V r (V), , V, V, , V, V, V , r (V) ³ 3 r (V) ³ 3.
1. G, . 15.23. 3 .
: G:
.
, 2, .
r 2 ij = aik bki,
r 2 ij ─ R2.
, , , :
.
, 3 , R2 R. ,
r 31,2 = r 1,1 r 21,2 + r 1,2 r 22,2 + r 1,3 r 23,2 + r 1,4 r 24,2 = 0*0 + 1*2 + 2*3 + 0*0 = 4.
, :
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.
R3 , , , x 1 x 2, 4 3: S1 = (x 1, x 2)(x 2, x 1)(x 1, x 2); S2 = (x 1, x 2)(x 2, x 4)(x 4, x 2); S3 = (x 1, x 3)(x 3, x 1)(x 1, x 2); S4 = (x 1, x 3)(x 3, x 4)(x 4, x 2).
2. , . 15.29, , , , .
. 15.29. G
: , . : S = (x 1, x 2), (x 2, x 6), (x 6 ─ x 2), (x 2 ─ x 7), (x 7 ─ x 6), (x 6 ─ x 2). , . , S = (x 1, x 2), (x 2, x 4), (x 4, x 6), (x 6, x 2), (x 2, x 7) . , . . , . C = (x 1, x 5), (x 5, x 3), (x 3, x 1), (x 1, x 8), (x 8, x 5), (x 5, x 1) . , , . () , . S = (x 1, x 2), (x 2, x 4), (x 4, x 6), (x 6, x 8), (x 8, x 3); C = (x 1, x 5), (x 5, x 3), (x 3, x 1).
3. , . 15.30 , .
: : U1 = {(x 3, x 6), (x 4, x 6), (x 4, x 7); U2 = {(x 4, x 10), (x 5, x 10)}; U3 = {(x 5, x 12)}; U4 = {(x 5, x 15)}. U : U = U1 È U2 È U3 È U4.
. 15.30. G
1. ?
2. ?
3. . ?
4. , , .
5. ?
6. ?
7. ?
8. , . .
9. . .
10. . .