A car service company employs a few people as a mechanic. According to the regulations of the company, each car requiring service is handled by a mechanic. The mechanic assigned to a car determines the service cost. All cars accepted for service at this company should pay the service cost except for those with full insurance. Only old cars have no full insurance. Besides, if the owner is an employee of the company, a 50% discount will be applied to all service expenses.

1. Create a knowledge base for this application using predicate logic.
2. What data is necessary to make an inference with this knowledge base?
3. Assume a customer named Hasan just brought his car to be serviced. Which inference method (forward/backward chaining) should be used to answer the question Should John pay the service costs?