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: Mary is not a writer. It is snowing or Susan is a bartender. Mary is a writer if and only if it is raining. If Susan were a bartender, then it is raining. It is not snowing or Robert is making tea.
Susan is a bartender or Robert is making tea can be inferred via the resolution rule. If Mary were a writer, then it is raining can be inferred via the biconditional elimination rule. If it rains, then Mary is a writer can be inferred via the biconditional elimination rule. It is not raining can be inferred via the biconditional elimination rule.