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: There is at least one x_15 for which x_15 will play a game if and only if x_15 will sleep. For all x_15, x_15 will sleep. For all x_15, x_15 will work. For all x_15, if x_15 works, then x_15 is a police officer.
For all x_15, x_15 is a police officer can be inferred via the universal modus ponens rule. For all x_15, x_15 will sleep and x_15 will work can be inferred via the universal conjunction rule. For all x_15, x_15 will work and x_15 will sleep can be inferred via the universal conjunction rule. There is at least one x_15 for which if x_15 plays a game, then x_15 is sleeping can be inferred via the existential biconditional elimination rule. There is at least one x_15 for which if x_15 sleeps, then x_15 is playing a game can be inferred via the existential biconditional elimination rule.