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: There is at least one x_4 for which x_4 is a server or x_4 is a musician. For all x_4, x_4 will write a letter. For all x_4, x_4 is not a server.
There is at least one x_4 for which x_4 is a musician can be inferred via the existential disjunctive syllogism rule.