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 y, if y were a taxi driver, then y is writing a letter. For all y, if y writes a letter, then y is cooking. For all y, if y cooks, then y is a taxi driver.
For all y, if y were a taxi driver, then y is cooking can be inferred via the universal transitivity rule. For all y, if y writes a letter, then y is a taxi driver can be inferred via the universal transitivity rule. For all y, if y cooks, then y is writing a letter can be inferred via the universal transitivity rule.