Consider the following premises. forall z: T(z) <-> R(z). ~q. t -> q. R(i_1) <-> t. Can we infer T(i_1) from them? If possible, name the inference rules being used at each step.
 From forall z: T(z) <-> R(z) we can infer T(i_1) <-> R(i_1) via universal instantiation. From t -> q, ~q we can infer ~t via modus tollens. From R(i_1) <-> t, ~t we can infer ~R(i_1) via biconditional elimination. Finally, from T(i_1) <-> R(i_1), ~R(i_1) we can infer ~T(i_1) via biconditional elimination, which contradicts T(i_1). Therefore, the answer is no.