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: ~q. u <-> R_23(a_23). q <-> r. forall x_23: ~R_23(x_23).
u -> R_23(a_23) can be inferred via the biconditional elimination rule. q -> r can be inferred via the biconditional elimination rule. R_23(a_23) -> u can be inferred via the biconditional elimination rule. r -> q can be inferred via the biconditional elimination rule. ~r can be inferred via the biconditional elimination rule.