chapter 8

Section 8.1

1. image

2. a. image

3. Use the composition rule (8.1.3) applied to a sequence of three statements.

a. image

4. a. First, prove {(x<10)(x5)}x:=4{x<5}:

image

Second, prove that (x < 10) ∧ ¬ (x ≥ 5) → (x < 5). This is a valid wff because of the equivalence ¬ (x ≥ 5) ≡ (x < 5). Thus the original wff is correct, by the if-then rule.

c.

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