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_18, x_18 is a doctor if and only if x_18 will drink water. For all x_18, x_18 will not drink water. John is a doctor if and only if Jennifer is a musician.
If John were a doctor, then Jennifer is a musician can be inferred via the biconditional elimination rule. If Jennifer were a musician, then John is a doctor can be inferred via the biconditional elimination rule. For all x_18, if x_18 were a doctor, then x_18 is drinking water can be inferred via the universal biconditional elimination rule. For all x_18, if x_18 drinks water, then x_18 is a doctor can be inferred via the universal biconditional elimination rule. For all x_18, x_18 is not a doctor can be inferred via the universal biconditional elimination rule.