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_2, x_2 will play tennis or x_2 is a janitor. There is at least one x_2 for which x_2 will not listen to a song. For all x_2, if x_2 plays tennis, then x_2 is listening to a song.
There is at least one x_2 for which x_2 will not play tennis can be inferred via the existential modus tollens rule.