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 y_4, if y_4 sleeps, then y_4 is playing squash. For all y_4, y_4 is not a politician. There is at least one y_4 for which y_4 will sleep or y_4 is not a politician. For all y_4, if y_4 plays squash, then y_4 is a politician.
For all y_4, y_4 will not play squash can be inferred via the universal modus tollens rule. For all y_4, if y_4 sleeps, then y_4 is a politician can be inferred via the universal transitivity rule. There is at least one y_4 for which if y_4 were a politician, then y_4 is sleeping can be inferred via the existential rewriting rule.