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_6, x_6 is not a bartender. For all x_6, x_6 will play tennis or x_6 is a bartender. For all x_6, if x_6 sleeps, then x_6 is not sad. For all x_6, x_6 will not play tennis or x_6 is sad.
For all x_6, x_6 is a bartender or x_6 is sad can be inferred via the universal resolution rule.