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: Sarah is not playing squash. For all y, y is a server if and only if y will play squash.
For all y, if y were a server, then y is playing squash can be inferred via the universal biconditional elimination rule. For all y, if y plays squash, then y is a server can be inferred via the universal biconditional elimination rule.