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_12, x_12 will take a plane if and only if x_12 will play squash. For all x_12, if x_12 were a bartender, then x_12 is playing squash. For all x_12, if x_12 takes a plane, then x_12 is a janitor. For all x_12, x_12 will not play a game. For all x_12, x_12 is a janitor if and only if x_12 will play a game.
For all x_12, if x_12 takes a plane, then x_12 is playing squash can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 were a janitor, then x_12 is playing a game can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 plays squash, then x_12 is taking a plane can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 plays a game, then x_12 is a janitor can be inferred via the universal biconditional elimination rule. For all x_12, x_12 is not a janitor can be inferred via the universal biconditional elimination rule.