6. A rule-based expert system has the following rules in its knowledge base. Rule 1: Y \& D Z Rule 2: X \& B \& E >Y Rule 3: A X Rule 4: C >L Rule 5: L \& M N (1) Explain briefly what are forward chaining and backward chaining. (2) Assuming the initial database of the expert system contains facts A, B, C, D and E, describe how to infer conclusion Z using forward chaining and backward chaining respectively