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: u or R_7(a_7). forall x_7: R_7(x_7) <-> S_7(x_7). u -> S_7(a_7).
R_1(a_7) -> u can be inferred via the rewriting rule. forall x_7: R_7(x_7) -> S_7(x_7) can be inferred via the universal biconditional elimination rule. forall x_7: S_7(x_7) -> R_7(x_7) can be inferred via the universal biconditional elimination rule.