Consider the following premises. forall x_15: P_15(x_15) <-> Q_15(x_15). forall x_15: P_12(x_15) -> P_15(x_15). forall x_15: P_12(x_15) <-> U(x_15). forall x_15: T_2(x_15) -> Q_15(x_15). forall x_15: U(x_15) or T_2(x_15). Can we infer forall x_15: P_15(x_15) <-> Q_15(x_15) from them? If possible, name the inference rules being used at each step.
That is one of the premises. Therefore, the answer is yes.