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: It is cloudy. It is sunny if and only if William is rich. For all x_17, x_17 will cook if and only if x_17 is rich. If William cooks, then it is not cloudy.
William is not cooking can be inferred via the modus tollens rule. If it is sunny, then William is rich can be inferred via the biconditional elimination rule. If William were rich, then it is sunny can be inferred via the biconditional elimination rule. For all x_17, if x_17 cooks, then x_17 is rich can be inferred via the universal biconditional elimination rule. For all x_17, if x_17 were rich, then x_17 is cooking can be inferred via the universal biconditional elimination rule.