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_9, x_9 will write a letter or x_9 is not an astronaut. There is at least one x_9 for which x_9 is an astronaut. For all x_9, x_9 will not write a letter.
Since the premises are contradictory, we can infer anything from them.