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, if x plays a game, then x is working. For all x, if x works, then x is playing a game.
For all x, x will play a game if and only if x will work can be inferred via the universal biconditional introduction rule. For all x, x will work if and only if x will play a game can be inferred via the universal biconditional introduction rule.