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: p_2 -> p_7. p_7 -> t. q <-> p_2. ~t.
~p_7 can be inferred via the modus tollens rule. q -> p_2 can be inferred via the biconditional elimination rule. p_2 -> q can be inferred via the biconditional elimination rule.