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: r <-> w. p_3. w -> ~s_3. p_3 -> s_3.
s_3 can be inferred via the modus ponens rule. r -> w can be inferred via the biconditional elimination rule. w -> r can be inferred via the biconditional elimination rule.