Consider the following premises. forall x_1: Q_3(x_1) or R(x_1). forall x_1: Q_3(x_1) -> U(x_1). forall x_1: U(x_1) -> Q_3(x_1). forall x_1: R(x_1) -> U(x_1). Can we infer U_1(a) from them? If possible, name the inference rules being used at each step.
We cannot infer that from the premises. Therefore the answer is no.