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 z for which if z were an astronaut, then z is driving a car. For all z, z will not drive a car. For all z, z is an astronaut if and only if z is a bartender.
There is at least one z for which z is not an astronaut can be inferred via the existential modus tollens rule. For all z, if z were an astronaut, then z is a bartender can be inferred via the universal biconditional elimination rule. For all z, if z were a bartender, then z is an astronaut can be inferred via the universal biconditional elimination rule.