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_6 for which x_6 is not a musician. For all x_6, x_6 is a musician if and only if x_6 is a sailor. For all x_6, if x_6 drives a car, then x_6 is a sailor.
For all x_6, if x_6 were a musician, then x_6 is a sailor can be inferred via the universal biconditional elimination rule. For all x_6, if x_6 were a sailor, then x_6 is a musician can be inferred via the universal biconditional elimination rule. There is at least one x_6 for which x_6 is not a sailor can be inferred via the existential biconditional elimination rule.