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: Patricia is not taking a plane. If it is overcast, then Patricia is taking a plane. Karen is an office clerk. If Patricia takes a plane, then it is overcast.
It is not overcast can be inferred via the modus tollens rule. Patricia is not taking a plane and Karen is an office clerk can be inferred via the conjunction rule. Karen is an office clerk and Patricia is not taking a plane can be inferred via the conjunction rule. It is overcast if and only if Patricia is taking a plane can be inferred via the biconditional introduction rule. Patricia is taking a plane if and only if it is overcast can be inferred via the biconditional introduction rule.