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_2, if x_2 were rich, then x_2 is reading a book. For all x_2, x_2 is rich if and only if x_2 is a politician. There is at least one x_2 for which x_2 will not read a book.
There is at least one x_2 for which x_2 is not rich can be inferred via the existential modus tollens rule. For all x_2, if x_2 were rich, then x_2 is a politician can be inferred via the universal biconditional elimination rule. For all x_2, if x_2 were a politician, then x_2 is rich can be inferred via the universal biconditional elimination rule.