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 sailor, then x_5 is an astronaut. There is at least one x_5 for which x_5 is a sailor or x_5 is not an astronaut. For all x_5, x_5 is not a sailor.
There is at least one x_5 for which if x_5 were an astronaut, then x_5 is a sailor can be inferred via the existential rewriting rule.