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: For all x_17, if x_17 were a sailor, then x_17 is a doctor. Karen is a sailor if and only if Elisabeth is a cashier. If Karen were a doctor, then Elisabeth is a cashier.
If Karen were a sailor, then Elisabeth is a cashier can be inferred via the biconditional elimination rule. If Elisabeth were a cashier, then Karen is a sailor can be inferred via the biconditional elimination rule.