80-211 Spring 2003

Assignment #8

Due on Friday, March 14.

Problem 1 (4 pts): Do problems 2, 3, 4, and 5 on page 147. Please make all explanations very brief.

Problem 2 (6 pts): Prove the follow sequents using the primitive rules of the predicate calculus and derived/primitive rules of the propositional calculus. Be sure to do both directions for problem (a) and problem (d).

(a) (x)(P→Fx) ┤├ P→(x)Fx

(b) $x(P & Fx) ├ P & $xFx

(c) $x(P v Fx) ├ P v $xFx

(d) $x(Fx→P) ┤├ (x)Fx→P