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: forall y: R(y). forall y: S_1(y) -> ~R(y). S_1(e_2) <-> t.
S_1(e_2) -> t can be inferred via the biconditional elimination rule. t -> S_1(e_2) can be inferred via the biconditional elimination rule. forall y: ~S_1(y) can be inferred via the universal modus tollens rule.