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: Robert is a sailor or it is not raining. If Robert were a sailor, then it is late. It is snowing if and only if it is late.
If it rains, then Robert is a sailor can be inferred via the rewriting rule. If it snows, then it is late can be inferred via the biconditional elimination rule. If it is late, then it is snowing can be inferred via the biconditional elimination rule.