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_17, x_17 is a doctor or x_17 will write a letter. For all x_17, x_17 is not a doctor. If William were an office clerk, then John is not a soldier. For all x_17, x_17 will not write a letter.
Since the premises are contradictory, we can infer anything from them.