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: For all x_4, x_4 will work if and only if x_4 is an electrician. For all x_4, x_4 will not work.
For all x_4, if x_4 works, then x_4 is an electrician can be inferred via the universal biconditional elimination rule. For all x_4, if x_4 were an electrician, then x_4 is working can be inferred via the universal biconditional elimination rule. For all x_4, x_4 is not an electrician can be inferred via the universal biconditional elimination rule.