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 were a musician, then y is a taxi driver. For all y, if y were a taxi driver, then y is a musician.
There is at least one y for which y is a musician if and only if y is a taxi driver can be inferred via the existential biconditional introduction rule. There is at least one y for which y is a taxi driver if and only if y is a musician can be inferred via the existential biconditional introduction rule.