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: u_2 -> p_8. ~s_3. p_8 <-> r_4. r_4 <-> s_3.
p_8 -> r_4 can be inferred via the biconditional elimination rule. r_4 -> s_3 can be inferred via the biconditional elimination rule. r_4 -> p_8 can be inferred via the biconditional elimination rule. s_3 -> r_4 can be inferred via the biconditional elimination rule. ~r_4 can be inferred via the biconditional elimination rule.