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_1 or ~t_3. t_3 <-> s_1. t_3 -> s_1.
t_3 -> s_1 can be inferred via the rewriting rule. t_3 -> s_1 can be inferred via the biconditional elimination rule. s_1 -> t_3 can be inferred via the biconditional elimination rule.