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_1: T(y_1) <-> P(y_1). P(a_12) <-> t. ~t.
P(a_12) -> t can be inferred via the biconditional elimination rule. t -> P(a_12) can be inferred via the biconditional elimination rule. ~P(a_12) can be inferred via the biconditional elimination rule. forall y_1: T(y_1) -> P(y_1) can be inferred via the universal biconditional elimination rule. forall y_1: P(y_1) -> T(y_1) can be inferred via the universal biconditional elimination rule.