What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: If James were a server, then Richard is writing a letter. If Robert climbs a mountain, then it is raining. Robert is climbing a mountain or Elisabeth is not happy. If it rains, then James is a server.
If Robert climbs a mountain, then James is a server can be inferred via the transitivity rule. If it rains, then Richard is writing a letter can be inferred via the transitivity rule. If Elisabeth were happy, then Robert is climbing a mountain can be inferred via the rewriting rule.