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. (PQ)R 2. RS 3. S 4. PU 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