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: forall x_15: U(x_15) -> S_15(x_15). ~q. q_8 <-> S_15(a_15). q <-> q_8.
q_8 -> S_15(a_15) can be inferred via the biconditional elimination rule. q -> q_8 can be inferred via the biconditional elimination rule. S_15(a_15) -> q_8 can be inferred via the biconditional elimination rule. q_8 -> q can be inferred via the biconditional elimination rule. ~q_8 can be inferred via the biconditional elimination rule.