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_1, if x_1 were a taxi driver, then x_1 is making tea. For all x_1, if x_1 plays a game, then x_1 is a taxi driver. There is at least one x_1 for which x_1 will play a game.
There is at least one x_1 for which x_1 is a taxi driver can be inferred via the existential modus ponens rule. For all x_1, if x_1 plays a game, then x_1 is making tea can be inferred via the universal transitivity rule.