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_13, if x_13 were a server, then x_13 is playing tennis. There is at least one x_13 for which x_13 will play a game or x_13 is a writer. For all x_13, x_13 is a server or x_13 is a musician. For all x_13, x_13 will not play a game. For all x_13, if x_13 were a musician, then x_13 is playing tennis.
There is at least one x_13 for which x_13 is a writer can be inferred via the existential disjunctive syllogism rule. For all x_13, x_13 will play tennis can be inferred via the universal disjunction elimination rule.