80-211 Spring 2003

Assignment #6

Due on Friday,
February, 28^{th} .

1. Do problems (n), (q), (s), (u) on page 103 of your text.

2. Using primitive rules or derived rules of the propositional calculus do problems (a), (c), (e) and (f) in exercise 2(i) on page 110 of your text.

3. Prove the following sequents using primitive rules or derived rules of the predicate and propositional calculus.

(a) "x(Gx → (Hx v ~Kx)), "x(Gx) ├ "x((Fx→Hx) v (Kx→Fx))

(b) "x(Gx→ (Hx & Fx)), ~Hm ├ ~Gm