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(x) <-> U(x). exists x: P(x) <-> U(x).
forall x: P(x) -> U(x) can be inferred via the universal biconditional elimination rule. exists x: P(x) -> U(x) can be inferred via the existential biconditional elimination rule. forall x: U(x) -> P(x) can be inferred via the universal biconditional elimination rule. exists x: U(x) -> P(x) can be inferred via the existential biconditional elimination rule.