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 for which x is a doctor if and only if x is a sailor. For all x, if x were a sailor, then x is a doctor.
There is at least one x for which if x were a doctor, then x is a sailor can be inferred via the existential biconditional elimination rule. There is at least one x for which if x were a sailor, then x is a doctor can be inferred via the existential biconditional elimination rule.