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, if x were a server, then x is a janitor. There is at least one x for which x is a janitor or x will not play a game. For all x, x will play a game. For all x, if x were a mechanic, then x is a server.
For all x, if x were a mechanic, then x is a janitor can be inferred via the universal transitivity rule. There is at least one x for which if x plays a game, then x is a janitor can be inferred via the existential rewriting rule.