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_13, x_13 will read a book or x_13 is not rich. For all x_13, if x_13 were rich, then x_13 is sleeping. There is at least one x_13 for which if x_13 reads a book, then x_13 is sleeping. For all x_13, if x_13 sleeps, then x_13 is rich.
There is at least one x_13 for which if x_13 reads a book, then x_13 is rich can be inferred via the existential transitivity rule. For all x_13, if x_13 were rich, then x_13 is reading a book can be inferred via the universal rewriting rule. For all x_13, x_13 is rich if and only if x_13 will sleep can be inferred via the universal biconditional introduction rule. For all x_13, x_13 will sleep if and only if x_13 is rich can be inferred via the universal biconditional introduction rule.