CSC240 Winter 2021 Midterm Assessment Question 5
YOUR NAME and STUDENT NUMBER
5. (10 marks) Recall that, for any set S, #S denotes the number of elements in S. For any n ∈ N, let [n] = {i ∈ N |1 ≤ i ≤ n}.
Give a well-ordering proof that, for all n ∈ N,
#(A∪B)=3n4n−1.
A⊆[n] B⊆[n]
Be sure to explicitly define the predicate you are using.
You may use the fact that #{A | A ⊆ [n]} = 2n. Solution:
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