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_1 -> q_1. ~q_9. t <-> q_9. q_1 -> t.
p_1 -> t can be inferred via the transitivity rule. t -> q_9 can be inferred via the biconditional elimination rule. q_9 -> t can be inferred via the biconditional elimination rule. ~t can be inferred via the biconditional elimination rule.