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_19, if x_19 were excited, then x_19 is sleeping. For all x_19, x_19 is not a lawyer. For all x_19, if x_19 writes a letter, then x_19 is playing squash. For all x_19, if x_19 drinks water, then x_19 is sleeping. There is at least one x_19 for which x_19 is a lawyer or x_19 will write a letter. For all x_19, x_19 will drink water or x_19 is excited.
There is at least one x_19 for which x_19 will write a letter can be inferred via the existential disjunctive syllogism rule. For all x_19, x_19 will sleep can be inferred via the universal disjunction elimination rule.