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 James climbs a mountain, then Susan is taking a plane. If it is overcast, then Susan is taking a plane. If Susan takes a plane, then James is climbing a mountain. James is climbing a mountain or it is overcast.
If it is overcast, then James is climbing a mountain can be inferred via the transitivity rule. Susan is taking a plane can be inferred via the disjunction elimination rule. James is climbing a mountain if and only if Susan is taking a plane can be inferred via the biconditional introduction rule. Susan is taking a plane if and only if James is climbing a mountain can be inferred via the biconditional introduction rule.