A propositional knowledge-base KB consisting of five sentences is given below (note that "/\" is used to denote "logical and", and "\/" is used to denote "logical or", and "~" is used to denote "logical negation"): 1. (~P /\ ~Q ) -> R 2. R -> S 3. ~S 4. P -> ~U 5. U

(a). (10 marks) Explain in English (in Steps!) that KB |= Q. (b). (10 marks) Show resolution steps that leads to KB |- Q. You should first convert the sentences in the KB into clauses.