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, y is not a carpenter. For all y, y is rich or y is not a mechanic. For all y, y is rich if and only if y is a carpenter.
For all y, if y were a mechanic, then y is rich can be inferred via the universal rewriting rule. For all y, if y were rich, then y is a carpenter can be inferred via the universal biconditional elimination rule. For all y, if y were a carpenter, then y is rich can be inferred via the universal biconditional elimination rule. For all y, y is not rich can be inferred via the universal biconditional elimination rule.