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_5, if x_5 were a server, then x_5 is sleeping. For all x_5, if x_5 were curious, then x_5 is a server. For all x_5, x_5 is a carpenter or x_5 is curious. For all x_5, if x_5 were a carpenter, then x_5 is sleeping. There is at least one x_5 for which if x_5 writes a letter, then x_5 is not sleeping.
For all x_5, if x_5 were curious, then x_5 is sleeping can be inferred via the universal transitivity rule.