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: For all y_4, y_4 will sleep if and only if y_4 will play a game. For all y_4, y_4 will sleep or y_4 is not a mechanic.
For all y_4, if y_4 were a mechanic, then y_4 is sleeping can be inferred via the universal rewriting rule. For all y_4, if y_4 sleeps, then y_4 is playing a game can be inferred via the universal biconditional elimination rule. For all y_4, if y_4 plays a game, then y_4 is sleeping can be inferred via the universal biconditional elimination rule.