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 it snows, then William is a janitor. If Mary makes tea, then it is not raining. It is raining. It is snowing.
William is a janitor can be inferred via the modus ponens rule. Mary is not making tea can be inferred via the modus tollens rule. It is raining and it is snowing can be inferred via the conjunction rule. It is snowing and it is raining can be inferred via the conjunction rule.