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_8 -> s_1. s_1 -> p_8. s_1 -> p_8.
p_8 <-> s_1 can be inferred via the biconditional introduction rule. p_8 <-> s_1 can be inferred via the biconditional introduction rule. s_1 <-> p_8 can be inferred via the biconditional introduction rule. s_1 <-> p_8 can be inferred via the biconditional introduction rule.