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_4 <-> r. q_4 -> r. ~q_4.
w and ~q_4 can be inferred via the conjunction rule. ~q_4 and w can be inferred via the conjunction rule. q_4 -> r can be inferred via the biconditional elimination rule. r -> q_4 can be inferred via the biconditional elimination rule. ~r can be inferred via the biconditional elimination rule.