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_3 -> u. q_15 -> u. u_3 or q_15. p_1 -> q_1. p_1.
q_1 can be inferred via the modus ponens rule. u can be inferred via the disjunction elimination rule.