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 Patricia drinks water, then Robert is taking a plane. Robert is taking a plane if and only if it is late. Mary is not driving a car. It is late if and only if Mary is driving a car.
If Robert takes a plane, then it is late can be inferred via the biconditional elimination rule. If it is late, then Mary is driving a car can be inferred via the biconditional elimination rule. If it is late, then Robert is taking a plane can be inferred via the biconditional elimination rule. If Mary drives a car, then it is late can be inferred via the biconditional elimination rule. It is not late can be inferred via the biconditional elimination rule.