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: p_1 -> U(d). forall y: U(y) <-> P_1(y). p_1.
U(d) can be inferred via the modus ponens rule. forall y: U(y) -> P_1(y) can be inferred via the universal biconditional elimination rule. forall y: P_1(y) -> U(y) can be inferred via the universal biconditional elimination rule.