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_4 for which if x_4 were a taxi driver, then x_4 is drinking water. For all x_4, x_4 will not read a book. For all x_4, if x_4 drinks water, then x_4 is reading a book. For all x_4, if x_4 reads a book, then x_4 is a taxi driver.
For all x_4, x_4 will not drink water can be inferred via the universal modus tollens rule. For all x_4, if x_4 drinks water, then x_4 is a taxi driver can be inferred via the universal transitivity rule. There is at least one x_4 for which if x_4 were a taxi driver, then x_4 is reading a book can be inferred via the existential transitivity rule. There is at least one x_4 for which if x_4 reads a book, then x_4 is drinking water can be inferred via the existential transitivity rule.