5.2.x. Exercise questions

1. Analyze each of the following sentences in as much detail as possible.
  a. Tom was late unless he left early.
  b. You’ll get a good picture only if you take the cap off the lens.
  c. Neither Ann nor Bill knew of it unless they both did.
  d. The bill will pass if the chairman supports it—unless public opinion runs heavily against it.
  e. Unless Ed is late, we’ll get started on time and finish early if there isn’t a lot of business.
  f. If Bob was under no obligation to help, he worked only if he was in a good mood and had nothing to do.
2. Synthesize idiomatic English sentences that express the propositions associated with the logical forms below by the intensional interpretations that follow them. These repeat 3 a, c, and d of 5.1.x. This time, you should look for ways of stating sentences using only if and unless.
  a. ¬ S → ¬ B
S: I’ll see it; B: I’ll believe it
  b. ¬ W ← ¬ (P ∧ ¬ B)
W: the set works; P: the set is plugged in; B: the set is broken
  c. ¬ (A ∨ B) → (G ← ¬ (C ∨ D))
A: Adams will back out; B: Brown will back out; G: the deal will go through; C: Collins will have trouble with financing; D: Davis will have trouble with financing
Glen Helman 15 Aug 2006