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: q <-> w. ~r. w <-> r.
q -> w can be inferred via the biconditional elimination rule. w -> r can be inferred via the biconditional elimination rule. w -> q can be inferred via the biconditional elimination rule. r -> w can be inferred via the biconditional elimination rule. ~w can be inferred via the biconditional elimination rule.