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 it is overcast, then it is windy. If it is windy, then it is overcast. Barbara is driving a car if and only if Elisabeth is an astronaut. Elisabeth is not an astronaut. If it is windy, then Barbara is driving a car.
If it is overcast, then Barbara is driving a car can be inferred via the transitivity rule. It is overcast if and only if it is windy can be inferred via the biconditional introduction rule. It is windy if and only if it is overcast can be inferred via the biconditional introduction rule. If Barbara drives a car, then Elisabeth is an astronaut can be inferred via the biconditional elimination rule. If Elisabeth were an astronaut, then Barbara is driving a car can be inferred via the biconditional elimination rule. Barbara is not driving a car can be inferred via the biconditional elimination rule.