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Unformatted text preview: a i in turn and deciding whether or not to include it in X . This gives us n independent choices between two possibilities: in X or out. The number of different subsets we can form is therefore 2 n . An alternative way of explaining this is to assign a or 1 to all the elements a i . Each subset corresponds to a unique binary number with n digits. There are 2 n such posibilities. Another proof will be given in the reasoning course next term, using the so-called induction principle. 2.2.5 Introducing Products The last set construct we consider is the product of two (or arbitrary n ) sets. This constructor forms an essential part of the deFnition of relation discussed in the next section. If we want to describe the relationship John loves Mary, then we require a way of talking about John and Mary at the 11...
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This note was uploaded on 01/02/2010 for the course MATH Math2009 taught by Professor Koskesh during the Spring '09 term at SUNY Empire State.
- Spring '09