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: It is late. John is a doctor if and only if it is cold. For all x_14, x_14 is not a doctor.
If John were a doctor, then it is cold can be inferred via the biconditional elimination rule. If it is cold, then John is a doctor can be inferred via the biconditional elimination rule.