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 x_6, if x_6 plays a game, then x_6 is sad. For all x_6, x_6 is sad if and only if x_6 will play a game.
For all x_6, if x_6 were sad, then x_6 is playing a game can be inferred via the universal biconditional elimination rule. For all x_6, if x_6 plays a game, then x_6 is sad can be inferred via the universal biconditional elimination rule.