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 y_1, y_1 is an electrician or y_1 is not excited. For all y_1, if y_1 were excited, then y_1 is an electrician. For all y_1, if y_1 were an electrician, then y_1 is excited.
For all y_1, if y_1 were excited, then y_1 is an electrician can be inferred via the universal rewriting rule. For all y_1, y_1 is excited if and only if y_1 is an electrician can be inferred via the universal biconditional introduction rule. For all y_1, y_1 is an electrician if and only if y_1 is excited can be inferred via the universal biconditional introduction rule.