80-211 Spring 2003
Due on Friday, March, 7th.
Note: For all these problems you can use the derived rules of the propositional calculus, but you may not use any derived rules of predicate logic.
Problem 1 (1 pt): Do problem 1-(c) on page 116 of your book.
Problem 2 (4 pts): On page 117 do problems (a), (d), (f), (g) of 2(i).
Problem 3 (5 pts): Prove the following sequents, and note that for (d) you must prove both directions:
(a) (x)(Fx→Gx) ├ ($x)Fx → ($x)Gx
(b) (x)~Fx ├ ~($x)Fx
(c) ~($x)(Fx & Gx) ├ (x)(Fx→ ~Gx)
(d) ($x)~Fx ┤├ ~(x)Fx