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_14 <-> p. forall x_20: R_20(x_20) -> S_20(x_20). s_2 -> R_20(a_20). p_14 -> s_2.
p_14 -> R_20(a_20) can be inferred via the transitivity rule. p_14 -> p can be inferred via the biconditional elimination rule. p -> p_14 can be inferred via the biconditional elimination rule.