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: Barbara is rich. If it is sunny, then it is late. William is driving a car if and only if it is late. William is not driving a car.
Barbara is rich and William is not driving a car can be inferred via the conjunction rule. William is not driving a car and Barbara is rich can be inferred via the conjunction rule. If William drives a car, then it is late can be inferred via the biconditional elimination rule. If it is late, then William is driving a car can be inferred via the biconditional elimination rule. It is not late can be inferred via the biconditional elimination rule.