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. q <-> p_6. p_6 -> s.
~p_6 can be inferred via the modus tollens rule. q -> p_6 can be inferred via the biconditional elimination rule. p_6 -> q can be inferred via the biconditional elimination rule.