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: w. P(a_7) -> ~w. forall z: P(z) <-> U(z).
~P(a_7) can be inferred via the modus tollens rule. forall z: P(z) -> U(z) can be inferred via the universal biconditional elimination rule. forall z: U(z) -> P(z) can be inferred via the universal biconditional elimination rule.