Consider the following premises. forall y: R(y) -> T_2(y). forall y: R(y) <-> T_2(y). Can we infer R(g_3) -> T_2(g_3) from them? If possible, name the inference rules being used at each step.
 From forall y: R(y) <-> T_2(y) we can infer forall y: T_2(y) -> R(y) via universal biconditional elimination. From forall y: T_2(y) -> R(y), forall y: R(y) -> T_2(y) we can infer forall y: T_2(y) <-> R(y) via universal biconditional introduction. From forall y: T_2(y) <-> R(y) we can infer T_2(g_3) <-> R(g_3) via universal instantiation. Finally, from T_2(g_3) <-> R(g_3) we can infer R(g_3) -> T_2(g_3) via biconditional elimination. Therefore, the answer is yes.