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 Michael takes a plane, then Richard is curious. Michael is taking a plane or Richard is not curious. Mary is climbing a mountain if and only if Richard is curious. Mary is not climbing a mountain.
If Richard were curious, then Michael is taking a plane can be inferred via the rewriting rule. If Mary climbs a mountain, then Richard is curious can be inferred via the biconditional elimination rule. If Richard were curious, then Mary is climbing a mountain can be inferred via the biconditional elimination rule. Richard is not curious can be inferred via the biconditional elimination rule.