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: Patricia is making tea or Robert is not happy. For all x_17, x_17 is a janitor if and only if x_17 will make tea. Robert is happy.
If Robert were happy, then Patricia is making tea can be inferred via the rewriting rule. For all x_17, if x_17 were a janitor, then x_17 is making tea can be inferred via the universal biconditional elimination rule. For all x_17, if x_17 makes tea, then x_17 is a janitor can be inferred via the universal biconditional elimination rule.