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 Joseph climbs a mountain, then William is sad. It is sunny. William is not sad.
Joseph is not climbing a mountain can be inferred via the modus tollens rule. It is sunny and William is not sad can be inferred via the conjunction rule. William is not sad and it is sunny can be inferred via the conjunction rule.