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. q_1 <-> p. q_1 -> t.
~q_1 can be inferred via the modus tollens rule. q_1 -> p can be inferred via the biconditional elimination rule. p -> q_1 can be inferred via the biconditional elimination rule.