Induction and Recursion Flashcards

(6 cards)

1
Q

What is the first thing you write down when doing induction?

A

Basis step, inductive step

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2
Q

What do you do in the basis step?

A

Show P(1) is true

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3
Q

What do you do in the inductive step?

A

Show P(k)→P(k+1) is true for all positive integers k

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4
Q

What is the basis step proving that for all positive integers n, it holds that n < 2ⁿ?

A

P(1) is true since 1 < 2¹ = 2

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5
Q

What is the inductive step proving that for all positive integers n, it holds that n < 2ⁿ?

A

Assume P(k) holds, k < 2ᵏ for an arbitrary positive integer k.
We show P(k+1) = k+1<2ᵏ⁺¹
By induction hypothesis, k<2ᵏ
Thus, k+1 < 2ᵏ+1 < 2ᵏ+2ᵏ = 2x2ᵏ = 2ᵏ⁺¹
This concludes the inductive step

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6
Q

What is ∑ᵏ⁺¹ᵢ₌₁ equal to by definition of summation?

A

∑ᵏ⁺¹ᵢ₌₁ = ∑ᵏ ᵢ₌₁ i + (k+1)

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