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: ~s. ~S(b). s or u. forall z: S(z) <-> T(z).
u can be inferred via the disjunctive syllogism rule. ~s and ~S(b) can be inferred via the conjunction rule. ~S(b) and ~s can be inferred via the conjunction rule. forall z: S(z) -> T(z) can be inferred via the universal biconditional elimination rule. forall z: T(z) -> S(z) can be inferred via the universal biconditional elimination rule.