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 z_1: S(z_1). forall z_1: S(z_1) -> R_3(z_1). P_1(a_1).
exists x: P_1(x) can be inferred via the existential generalization rule. forall z_1: R_3(z_1) can be inferred via the universal modus ponens rule.