Элементы дискретной математики. Часть I - 92 стр.

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A
1
,...,A
n
,
A
i
i =1,...,n.
A
1
,...,A
n
A
1
,...,A
n
a
1
,...,a
n
a
i
A
i
,
1 i n,
a
i
= a
j
i = j. a
i
A
i
.
A
1
= {1, 2, 3},
A
2
= {1, 2, 4},
A
3
= {1, 2, 5},
A
4
= {3, 4, 5, 6},
A
5
= {3, 4, 5, 6}.
1, 2, 5, 3, 4 A
1
,A
2
,A
3
,A
4
,A
5
.
B
1
= {1, 2},
B
2
= {1, 2},
B
3
= {1, 2},
B
4
= {3, 4, 5, 6},
B
5
= {3, 4, 5, 6}.
n A
i
n
a
1
,...,a
n
A
1
,...,A
n
J ⊆{1,...,n}
jJ
A
j
≥|J|. (1)