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_11 for which x_11 is a bartender if and only if x_11 will drive a car. For all x_11, x_11 is a musician if and only if x_11 is a bartender. For all x_11, x_11 is a mechanic and x_11 is happy. For all x_11, if x_11 were a musician, then x_11 is not a mechanic.
For all x_11, x_11 is a mechanic can be inferred via the universal simplification rule. For all x_11, x_11 is happy can be inferred via the universal simplification rule. For all x_11, if x_11 were a musician, then x_11 is a bartender can be inferred via the universal biconditional elimination rule. There is at least one x_11 for which if x_11 were a bartender, then x_11 is driving a car can be inferred via the existential biconditional elimination rule. For all x_11, if x_11 were a bartender, then x_11 is a musician can be inferred via the universal biconditional elimination rule. There is at least one x_11 for which if x_11 drives a car, then x_11 is a bartender can be inferred via the existential biconditional elimination rule.