Consider the following premises. exists y_3: U(y_3) <-> S_3(y_3). forall y_3: P(y_3) <-> U(y_3). forall y_3: ~P(y_3). Can we infer exists y_3: U(y_3) <-> S_3(y_3) from them? If possible, name the inference rules being used at each step.
That is one of the premises. Therefore, the answer is yes.