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, if y were an office clerk, then y is happy. For all y, if y were a poet, then y is an office clerk. For all y, y is not happy. For all y, y is a poet or y is not an office clerk.
For all y, y is not an office clerk can be inferred via the universal modus tollens rule. For all y, if y were a poet, then y is happy can be inferred via the universal transitivity rule. For all y, if y were an office clerk, then y is a poet can be inferred via the universal rewriting rule.