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 -> q. p_6 -> q. ~w. q -> w. q -> p_6.
~q can be inferred via the modus tollens rule. w -> p_6 can be inferred via the transitivity rule. p_6 -> w can be inferred via the transitivity rule. w <-> q can be inferred via the biconditional introduction rule. p_6 <-> q can be inferred via the biconditional introduction rule. q <-> w can be inferred via the biconditional introduction rule. q <-> p_6 can be inferred via the biconditional introduction rule.