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: s -> p_4. u -> P(a_17). p_4 <-> u. P(a_17) -> u. forall x: ~P(x).
p_4 -> u can be inferred via the biconditional elimination rule. u -> p_4 can be inferred via the biconditional elimination rule.