Unformatted text preview: that the three numbers are all diﬀerent? 3. (2 points) Suppose that n is a positive integer. Let S be a set with 2 n elements. Prove that if n > 1, then Sub ( S,n ) > 2 n . 4. (2 points) (Challenge!) Suppose that n is a positive integer. Let S be a set with 2 n elements. How many ways are there to partition S into n pairs. In other words, how many ways are there to choose n pairs from the set S , such that every member of S is a member of exactly one pair?...
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 Fall '08
 Weissman
 Math, Natural number, Prime number, positive integer

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