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: P_1(x) <-> W(x). ~W(a). r.
~W(a) and r can be inferred via the conjunction rule. r and ~W(a) can be inferred via the conjunction rule. forall x: P_1(x) -> W(x) can be inferred via the universal biconditional elimination rule. forall x: W(x) -> P_1(x) can be inferred via the universal biconditional elimination rule.