What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? There is at least one y for which y will play tennis if and only if y is a taxi driver. For all y, if y plays tennis, then y is working. For all y, if y plays tennis, then y is a taxi driver.
There is at least one y for which if y plays tennis, then y is a taxi driver. There is at least one y for which if y were a taxi driver, then y is playing tennis.