HOMEWORK 3

Due: In Lecture, Friday, March 8, 1996.

- (6) Use truth tables to show that the following sentences are valid,
and thus that the equivalences hold. [Text, Exercise 6.2, p. 180]
- (P => Q) <=> (~P v Q)
- ~(P & Q) <=> (~P v ~Q)
- P & (Q v R) <=> (P & Q) v (P & R)

- Consider Exercise 6.5 of the text (p. 181).
- (3) Choose atomic propositions to use to represent the information in this exercise, and give the intensional semantics of those atomic propositions.
- (6) The text asks if you can prove that the unicorn is mythical, magical and/or horned. For each one of these three that you can prove, give the Fitch-style proof. For each one that you cannot prove, provide a falsifying assignment of truth values to the atomic propositions. In all cases, use the representation of atomic propositions you chose above.

Back to CS4/572 Syllabus.

Thu Jan 25 16:32:27 EST 1996