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, y will sleep if and only if y will play squash. There is at least one y for which y will play squash or y will not sleep.
There is at least one y for which if y sleeps, then y is playing squash can be inferred via the existential rewriting rule. For all y, if y sleeps, then y is playing squash can be inferred via the universal biconditional elimination rule. For all y, if y plays squash, then y is sleeping can be inferred via the universal biconditional elimination rule.