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: t or ~u. t -> u. u_3 <-> q_3. ~u_3. q_3 <-> u.
u -> t can be inferred via the rewriting rule. u_3 -> q_3 can be inferred via the biconditional elimination rule. q_3 -> u can be inferred via the biconditional elimination rule. q_3 -> u_3 can be inferred via the biconditional elimination rule. u -> q_3 can be inferred via the biconditional elimination rule. ~q_3 can be inferred via the biconditional elimination rule.