CS676: Knowledge Representation Fall, 1997

Homework 3
Due at start of class, October 16, 1997

Stuart C. Shapiro
Department of Computer Science
State University of New York at Buffalo

---

1. Using the Rules of Inference of the FR system, as given in Chapter 3.2 of the text, prove
   ((P -> Q) & (Q -> R)) -> (P -> R)

2. Prove that (L(A) & L(A => B)) => L(B) is valid in modal logics.

3. Prove that (L(A) & (A => B)) => L(B) is not valid in modal logics.

---

Stuart C. Shapiro <shapiro@cs.buffalo.edu>