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_3: S(y_3) <-> R_1(y_3). S(a) or t. t <-> R_1(a).
t -> R_1(a) can be inferred via the biconditional elimination rule. R_1(a) -> t can be inferred via the biconditional elimination rule. forall y_3: S(y_3) -> R_1(y_3) can be inferred via the universal biconditional elimination rule. forall y_3: R_1(y_3) -> S(y_3) can be inferred via the universal biconditional elimination rule.