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: There is at least one y for which if y works, then y is playing squash. For all y, if y were a taxi driver, then y is working. For all y, if y plays squash, then y is a taxi driver.
For all y, if y plays squash, then y is working can be inferred via the universal transitivity rule. There is at least one y for which if y works, then y is a taxi driver can be inferred via the existential transitivity rule. There is at least one y for which if y were a taxi driver, then y is playing squash can be inferred via the existential transitivity rule.