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, if y_1 makes tea, then y_1 is a janitor. There is at least one y_1 for which y_1 is not a carpenter. For all y_1, if y_1 were a carpenter, then y_1 is making tea. For all y_1, if y_1 were a janitor, then y_1 is a carpenter.
There is at least one y_1 for which y_1 is not a janitor can be inferred via the existential modus tollens rule. For all y_1, if y_1 makes tea, then y_1 is a carpenter can be inferred via the universal transitivity rule. For all y_1, if y_1 were a carpenter, then y_1 is a janitor can be inferred via the universal transitivity rule. For all y_1, if y_1 were a janitor, then y_1 is making tea can be inferred via the universal transitivity rule.