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 Robert climbs a mountain, then Barbara is drinking water. If Robert climbs a mountain, then Michael is sleeping. If Michael sleeps, then Robert is climbing a mountain. If Barbara drinks water, then Michael is sleeping.
If Robert climbs a mountain, then Michael is sleeping can be inferred via the transitivity rule. If Michael sleeps, then Barbara is drinking water can be inferred via the transitivity rule. If Barbara drinks water, then Robert is climbing a mountain can be inferred via the transitivity rule. Robert is climbing a mountain if and only if Michael is sleeping can be inferred via the biconditional introduction rule. Michael is sleeping if and only if Robert is climbing a mountain can be inferred via the biconditional introduction rule.