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: w_1 -> s_4. ~w_1 -> s. ~s_3. s_4 <-> s_3.
s_4 -> s_3 can be inferred via the biconditional elimination rule. s_3 -> s_4 can be inferred via the biconditional elimination rule. ~s_4 can be inferred via the biconditional elimination rule.