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India Contests
Regional Mathematical Olympiad
1997 India Regional Mathematical Olympiad
6
6
Part of
1997 India Regional Mathematical Olympiad
Problems
(1)
Find the number of unordered pairs
Source: Indian RMO 1997 PROBLEM 6
10/26/2005
Find the number of unordered pairs
{
A
,
B
}
\{ A,B \}
{
A
,
B
}
of subsets of an n-element set
X
X
X
that satisfies the following: (a)
A
≠
B
A \not= B
A
=
B
(b)
A
∪
B
=
X
A \cup B = X
A
∪
B
=
X
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