Homework 7

Handout based on section 4.3; includes exercise 12 from that section and 5 proofs of implications and biconditionals taken from that section.

Just do parts a,c,e,g of problem 12.

Due Monday, March 6.

Just to be completely clear, here are the statements to be formally
proved on the first page (mod the typos I inevitably introduced on
this first pass -- one point to the first student who points out each
typo :-):

(Ex.~Px) <-> ~(Ax.Px)

(Ex.(Px | Qx)) <-> ((Ex.Px) | (Ex.Qx))

(Ax.(Px | S)) <-> (Ax.Ps) | S  (where x does not occur free in S!)

(Ax.(Px -> Qx)) -> ((Ex.Px) -> (Ex.Qx))

(Ey.(Ax.Rxy)) -> (Ax.(Ey.Rxy))