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: p_18 <-> q_18. ~S_4(h_4). p_18 -> P_2(h_4). forall y: P_2(y) <-> S_4(y).
p_18 -> q_18 can be inferred via the biconditional elimination rule. q_18 -> p_18 can be inferred via the biconditional elimination rule. forall y: P_2(y) -> S_4(y) can be inferred via the universal biconditional elimination rule. forall y: S_4(y) -> P_2(y) can be inferred via the universal biconditional elimination rule.