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 -> p_1. s_4 -> p_1. p_1 -> s_4.
p -> s_4 can be inferred via the transitivity rule. s_4 <-> p_1 can be inferred via the biconditional introduction rule. p_1 <-> s_4 can be inferred via the biconditional introduction rule.