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_4 <-> p. forall x_17: P_17(x_17) or ~Q_17(x_17). u_4 or Q_17(a_15). P_17(a_15) -> p.
R_1(a_15) -> u_4 can be inferred via the rewriting rule. u_4 -> p can be inferred via the biconditional elimination rule. p -> u_4 can be inferred via the biconditional elimination rule. forall x_17: Q_17(x_17) -> P_17(x_17) can be inferred via the universal rewriting rule.