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_4 -> p_1. p_1 -> t_4.
t_4 <-> p_1 can be inferred via the biconditional introduction rule. p_1 <-> t_4 can be inferred via the biconditional introduction rule.