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_12, if x_12 were rich, then x_12 is taking a plane. David is not taking a plane. For all x_12, x_12 will read a book if and only if x_12 is rich.
For all x_12, if x_12 reads a book, then x_12 is rich can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 were rich, then x_12 is reading a book can be inferred via the universal biconditional elimination rule.