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 Susan sleeps, then Susan is cooking. Susan is sleeping if and only if Richard is a police officer. If Susan cooks, then it is snowing. If it snows, then Richard is a police officer.
If Susan sleeps, then it is snowing can be inferred via the transitivity rule. If Susan cooks, then Richard is a police officer can be inferred via the transitivity rule. If Susan sleeps, then Richard is a police officer can be inferred via the biconditional elimination rule. If Richard were a police officer, then Susan is sleeping can be inferred via the biconditional elimination rule.