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: Richard is not a bartender. If Richard doesn't cook, then Barbara is working. For all x_11, x_11 is a bartender if and only if x_11 will cook.
For all x_11, if x_11 were a bartender, then x_11 is cooking can be inferred via the universal biconditional elimination rule. For all x_11, if x_11 cooks, then x_11 is a bartender can be inferred via the universal biconditional elimination rule.