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: ~t. t <-> q. r_1.
~t and r_1 can be inferred via the conjunction rule. r_1 and ~t can be inferred via the conjunction rule. t -> q can be inferred via the biconditional elimination rule. q -> t can be inferred via the biconditional elimination rule. ~q can be inferred via the biconditional elimination rule.