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, y is a taxi driver or y is a doctor. For all y, y is a taxi driver if and only if y will listen to a song. There is at least one y for which y will not listen to a song.
For all y, if y were a taxi driver, then y is listening to a song can be inferred via the universal biconditional elimination rule. For all y, if y listens to a song, then y is a taxi driver can be inferred via the universal biconditional elimination rule. There is at least one y for which y is not a taxi driver can be inferred via the existential biconditional elimination rule.