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_3, if y_3 were a lawyer, then y_3 is making tea. For all y_3, y_3 is a lawyer if and only if y_3 is bored. For all y_3, if y_3 makes tea, then y_3 is a mechanic.
For all y_3, if y_3 were a lawyer, then y_3 is a mechanic can be inferred via the universal transitivity rule. For all y_3, if y_3 were a lawyer, then y_3 is bored can be inferred via the universal biconditional elimination rule. For all y_3, if y_3 were bored, then y_3 is a lawyer can be inferred via the universal biconditional elimination rule.