Assignment 4

Due Tuesday, February 2nd in class.

1. AIMA 6.3
2. AIMA 6.10
3. AIMA 6.12

4. Modus ponens is the rule that if (P AND (P IMPLIES Q)) then Q.
   Abduction is the inference rule that ((P IMPLIES Q) AND Q) then P.
   Modus tollens is the rule that if (~Q AND (P IMPLIES Q)) then ~P.

   a) Prove that modus ponens is sound for propositional logic.
   b) Prove that abduction is not sound.
   c) Show that modus tollens is sound.