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_18, x_18 will not sleep. For all x_18, if x_18 cooks, then x_18 is sleeping. For all x_18, x_18 is a sailor or x_18 is happy. There is at least one x_18 for which if x_18 were a sailor, then x_18 is cooking.
For all x_18, x_18 will not cook can be inferred via the universal modus tollens rule. There is at least one x_18 for which if x_18 were a sailor, then x_18 is sleeping can be inferred via the existential transitivity rule.