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_8, x_8 is a server if and only if x_8 will cook. If Richard were an office clerk, then Mary is cooking. Mary is a server or Richard is an office clerk.
For all x_8, if x_8 were a server, then x_8 is cooking can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 cooks, then x_8 is a server can be inferred via the universal biconditional elimination rule.