What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_4, if x_4 takes a plane, then x_4 is playing squash. For all x_4, if x_4 plays squash, then x_4 is a taxi driver. For all x_4, if x_4 were a taxi driver, then x_4 is taking a plane.
For all x_4, if x_4 takes a plane, then x_4 is a taxi driver. For all x_4, if x_4 plays squash, then x_4 is taking a plane. For all x_4, if x_4 were a taxi driver, then x_4 is playing squash.