MathDB
Problems
Contests
National and Regional Contests
India Contests
India National Olympiad
1996 India National Olympiad
4
4
Part of
1996 India National Olympiad
Problems
(1)
Find the triples
Source: INMO 1996 Problem 4
10/6/2005
Let
X
X
X
be a set containing
n
n
n
elements. Find the number of ordered triples
(
A
,
B
,
C
)
(A,B, C)
(
A
,
B
,
C
)
of subsets of
X
X
X
such that
A
A
A
is a subset of
B
B
B
and
B
B
B
is a proper subset of
C
C
C
.
combinatorics unsolved
combinatorics