Recitation 4
Definitions
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x is an element of A
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x is not an element of A
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A is a subset of B iff every element of A is in B
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the empty set is always an element
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the set is a subset of itself
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A is a proper subset of B if there is an element of B that is not in A
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the power set of A which is the set of all subsets of A
Example Problems
Answer True or False
{
}
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True
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False
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True since every element in C is in A
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True since there are elements in A that aren’t in C
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False
Set Operators
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elements in A or B (can be in either)
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element in A and B (have to be in both)
Examples on Sets
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= {1,2,3,4,5,6,7}
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= {1}
Review
Problem 13 on HW
Problem 17 Chapter 1.7 Show that if
