Consider the following premises. p_11 -> p. s_3 <-> p. p_11 or t. t -> p. Can we infer s_3 from them? If possible, name the inference rules being used at each step.
 From p_11 -> p, t -> p, p_11 or t we can infer p via disjunction elimination. From s_3 <-> p we can infer p -> s_3 via biconditional elimination. Finally, from p -> s_3, p we can infer s_3 via modus ponens. Therefore, the answer is yes.