What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: s_4 -> ~q_7. s_4 <-> t. q_7. p <-> t.
~s_4 can be inferred via the modus tollens rule. s_4 -> t can be inferred via the biconditional elimination rule. p -> t can be inferred via the biconditional elimination rule. t -> s_4 can be inferred via the biconditional elimination rule. t -> p can be inferred via the biconditional elimination rule.