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: r or u. ~r. ~u_3. u_3 <-> p.
u can be inferred via the disjunctive syllogism rule. ~r and ~u_3 can be inferred via the conjunction rule. ~u_3 and ~r can be inferred via the conjunction rule. u_3 -> p can be inferred via the biconditional elimination rule. p -> u_3 can be inferred via the biconditional elimination rule. ~p can be inferred via the biconditional elimination rule.