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_12 for which if x_12 were a doctor, then x_12 is not reading a book. For all x_12, x_12 will read a book. For all x_12, x_12 is a doctor if and only if x_12 will cook.
There is at least one x_12 for which x_12 is not a doctor can be inferred via the existential modus tollens rule. For all x_12, if x_12 were a doctor, then x_12 is cooking can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 cooks, then x_12 is a doctor can be inferred via the universal biconditional elimination rule.