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 x_7, x_7 is a mechanic if and only if x_7 is poor. If William were a mechanic, then it is raining. It is not raining.
William is not a mechanic can be inferred via the modus tollens rule. For all x_7, if x_7 were a mechanic, then x_7 is poor can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 were poor, then x_7 is a mechanic can be inferred via the universal biconditional elimination rule.