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: It is raining if and only if David is climbing a mountain. It is not raining. If David climbs a mountain, then John is an artist. If John were an artist, then it is raining.
John is not an artist can be inferred via the modus tollens rule. If David climbs a mountain, then it is raining can be inferred via the transitivity rule. If it rains, then David is climbing a mountain can be inferred via the biconditional elimination rule. If David climbs a mountain, then it is raining can be inferred via the biconditional elimination rule. David is not climbing a mountain can be inferred via the biconditional elimination rule.