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_13 <-> S_21(a_21). p_8 <-> p_13. forall x_21: R_21(x_21) <-> S_21(x_21). ~R_21(a_21).
p_13 -> S_21(a_21) can be inferred via the biconditional elimination rule. p_8 -> p_13 can be inferred via the biconditional elimination rule. S_21(a_21) -> p_13 can be inferred via the biconditional elimination rule. p_13 -> p_8 can be inferred via the biconditional elimination rule. forall x_21: R_21(x_21) -> S_21(x_21) can be inferred via the universal biconditional elimination rule. forall x_21: S_21(x_21) -> R_21(x_21) can be inferred via the universal biconditional elimination rule.