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 musician if and only if x is a bartender. For all x, if x were a musician, then x is a bartender. For all x, if x were a bartender, then x is a musician. For all x, x is not a bartender.
For all x, x is not a musician can be inferred via the universal modus tollens rule. For all x, x is a musician if and only if x is a bartender can be inferred via the universal biconditional introduction rule. For all x, x is a bartender if and only if x is a musician can be inferred via the universal biconditional introduction rule. There is at least one x for which if x were a musician, then x is a bartender can be inferred via the existential biconditional elimination rule. There is at least one x for which if x were a bartender, then x is a musician can be inferred via the existential biconditional elimination rule. There is at least one x for which x is not a musician can be inferred via the existential biconditional elimination rule.