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: There is at least one x_8 for which x_8 is a poet or x_8 is a mechanic. For all x_8, x_8 is not rich. For all x_8, x_8 is rich if and only if x_8 is a poet. For all x_8, if x_8 were a poet, then x_8 is rich.
For all x_8, x_8 is not a poet can be inferred via the universal modus tollens rule. For all x_8, if x_8 were rich, then x_8 is a poet can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 were a poet, then x_8 is rich can be inferred via the universal biconditional elimination rule. For all x_8, x_8 is not a poet can be inferred via the universal biconditional elimination rule.