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: There is at least one x_10 for which x_10 is a doctor if and only if x_10 is a police officer. For all x_10, x_10 is not a doctor. For all x_10, x_10 is a police officer or x_10 will not drink water.
For all x_10, if x_10 drinks water, then x_10 is a police officer can be inferred via the universal rewriting rule. There is at least one x_10 for which if x_10 were a doctor, then x_10 is a police officer can be inferred via the existential biconditional elimination rule. There is at least one x_10 for which if x_10 were a police officer, then x_10 is a doctor can be inferred via the existential biconditional elimination rule. There is at least one x_10 for which x_10 is not a police officer can be inferred via the existential biconditional elimination rule.