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_7, if x_7 were a soldier, then x_7 is not sleeping. For all x_7, x_7 will sleep. There is at least one x_7 for which x_7 will read a book if and only if x_7 is a soldier.
For all x_7, x_7 is not a soldier can be inferred via the universal modus tollens rule. There is at least one x_7 for which if x_7 reads a book, then x_7 is a soldier can be inferred via the existential biconditional elimination rule. There is at least one x_7 for which if x_7 were a soldier, then x_7 is reading a book can be inferred via the existential biconditional elimination rule.